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Ron Rivest Suggests Probability-Based Micropayments
Karl J. Smith writes "Rivest has solved the micropayments problem with encryption and statistics. You throw away some transactions so that you don't have to pay bank fees, and process the rest. Hiawatha Bray has written an article and Rivest's new company is PepperCoin."
Yes, that is the way to make micropayments take off: patent them.
Most people's number skills are so poor that they probably won't understanding or trust it.
That's cool, it'll be a new way for a company to justify high losses: 'no sir, our product isn't crap, we are selling many many; we just are unlucky with Peppercoin, only getting useless tokens...'
Tsuyoikoto ha taisetsu da ne, dakedo namida mo hitsuyousa (Strength is an important thing, but tears too are necessary)
Ok, randomization has its uses, but what advantage does it have over just waiting till the micropayments sum up to $10 and sending them then?
Once the means to collect it was in place.. see what happened?
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
Sounds, from reading that short article, like the merchants must trust Peppercoin? Why should they?
Belief is the currency of delusion.
In cause we manage to /. the server
Solving the problem of micropayments
By Hiawatha Bray, Globe Staff, 2/17/2003
IT professor Ron Rivest has come up with a new way to throw away money on the Internet. With luck, it'll make him a fortune. Rivest is one of the three people who devised the encryption system that allows us to transmit our credit-card information safely over the Internet. The company that grew out of this work, Bedford-based RSA Security Inc., is one of the leaders in the field. He's a fellow of the American Academy of Arts and Sciences and the Association of Computing Machinery. Put it this way: Rivest knows what he's doing. So what's all this about throwing away money?
Actually, it's a fascinating proposal for solving one of the toughest -- and smallest -- problems of Internet commerce. It's easy to buy a $20 CD online, or a $100 hard drive or a $20,000 car. But how do you buy something online when it only costs a buck or two?
This is what's called a micropayment, and it turns out to be remarkably difficult to do. Entrepreneurs have been banging their heads against this problem for the past half-decade or more, and with good reason. There are lots of desirable digital products that might sell like popcorn if there were a practical way to pay for them. Music, for instance. Some subscription services will let you download tunes at 50 cents apiece, but you have to pay a subscription fee as well. We're still waiting for a service that lets anybody drop by at any time, and purchase a single song.
This is because it costs so much to process a single financial transaction. Most Internet shopping happens with a credit card. The merchant selling the goods must pay a transaction fee to the credit card issuer. This usually amounts to a few percent of the sale price, plus a flat fee of 25 cents or so.
But this flat fee is the same no matter the size of the purchase. When the merchant is selling Tom Clancy novels at $30 apiece, the fee doesn't matter. If it's an MP3 of the latest single from Sheryl Crow, that fee will eat up all the seller's profits, maybe even put him in the red.
''You can't do small payments with credit cards,'' said Rivest. ''From the merchant's point of view, you probably can't do under $5 and make a profit.''
What's needed is a method that slashes the cost of the transaction. Enter Rivest, his colleague and fellow computer scientist Silvio Micali, and their new company, Peppercoin Inc., which plans to solve the problem with doses of encryption and statistics.
The service will be free to consumers, who sign up with Peppercoin and provide a credit card number. Now the user can go to any Peppercoin retailer and purchase a single, very cheap item -- an MP3 song priced at 50 cents, for instance. By clicking on a link, the music gets downloaded to the customer's computer. The merchant gets a Peppercoin -- a sort of electronic token that's got the customer's digital signature embedded in it.
What's the token worth to the merchant? It depends. Peppercoin uses an algorithm that assigns a value to the token. Actually it assigns one of two values. Either the token is worth some preset amount -- say, $10 -- or it's worth nothing at all. When the token is worthless, the merchant throws it away. When it's not, the merchant collects $10 from Peppercoin, even if the customer only spent 50 cents.
It seems utterly nutty until you apply this method to millions of 50-cent transactions every month. Maybe 5 percent of these transactions will be sent to Peppercoin, which processes them through the credit card system. The rest are thrown away. This keeps transaction costs way low. And the transactions that are processed have a value of $10 apiece, which brings in cash to make up for the 95 percent that were thrown away. Spread over millions of purchases, it all averages out.
But even if Rivest's math is correct, the success of Peppercoin is far from assured. The dot-com graveyard has a special section for companies like Digicash and Cybercent that failed to solve the micropayment puzzle.
''A payment system is a real chicken-and-egg problem,'' said Rivest. Consumers won't embrace the system unless lots of merchants accept it; merchants won't sign onto the system unless the customers are there. Peppercoin hopes to break the cycle by signing up some major media companies in time for its debut later this year.
Letting consumers buy hit music recordings for a buck or less, without charging $10 a month in subscription fees, could be just the thing to ignite the micropayment market. And if more consumers sign up for Peppercoin, more vendors will start offering products -- magazine articles, digital games, even those annoying cellphone ringtones. Many of these goodies will be items that are presently given away, because there's no efficient way to charge for them.
With Peppercoin, companies will be able to make us pay. And at the microprices made possible by his software, Rivest figures millions of us will be happy to let him throw our money away.
Hiawatha Bray can be reached at bray@globe.com.
This story ran on page C4 of the Boston Globe on 2/17/2003.
© Copyright 2003 Globe Newspaper Company
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
But what is the difference of this and PayPal???? Ok there is some more math.
But I thought part of the problem was using PayPal is that PayPal is an external service that is not as recognized as Visa, Mastercard, or American Express (plus some others).
And this service does not seem to solve that problem for me. I thought when I started reading the article that it was going to somehow have some magic receipe for using my ALREADY accepted credit card....
"You can't make a race horse of a pig"
"No," said Samuel, "but you can make very fast pig"
So what makes Ron Rivest thinks he might be able to solve this where other failed?
A key success factor of this business is trust. But unfortunaly for non-geeks, trust is hardly based on transaction security, but merely on the wealth of the company.
Microsoft tokens won't have the same trust factor as Linux tokens (for example), and customers won't buy tokens that could well be worth less than nothing, if the market decides that way.
Would you really invest a penny (because that's what is's all about : invest money) in peppercoin?
Violence is the last refuge of the incompetent - Salvor Hardin
Micropayments are ok
But what we REALLY need are micro bills
So we have *drum roll* another internet currency! Hoorah, the old ones did so well. Noone has the funds to get to critical mass now - you need a LOT of vendors to accept the currency for consumers to be interested. Not that VISA/MC would just sit there if you tried to get to this level.
See beenz.com (oh, it isn't there?) for history of such schemes.
"To any truly impartial person, it would be obvious that I am right."
No, it's a lottery on whether the merchant gets PAID or not. However, the assumption is that even if he doesn't get paid on your transaction, he'll get paid enough next time to make up for it.
What is the point of a retailer collecting these PepperCoins, then sending them in, with 5% of them being worth $10.00, and 95% of them being worthless? If you're going to have a clearing-house, why the hell wouldn't you just have the retailers collect the PepperCoins and send them in for a guaranteed 50c each, but just not do it until you've collected at least 20 of them?? It'd have the same "avoiding credit card fees" effect, but without the stupid randomness which, even if it does balance out perfectly over lots of transactions, will completely turn off the vast majority of retailers.
I don't understand this. Does it mean that sometimes my card will be charged, and sometimes not? If I buy just one MP3 (or whatever) online, could I be the unlucky Joe who pays for 9 other people too?
When I am king, you will be first against the wall.
This is a hard sell for all involved i think.
For the Merchant
"....That's right Mr. Merchant we will allow these anonymous customers to log on to your system you give them your products, and they can pay with our tokens that are worthless 95% of the time, but you'll be ok in the long run. Um no we are not like those other dot.com companies that are not around for the long run..."
As well as that what is the advantage to the customer?
I can see how the law of averages works (or works more quickly) for the Merchant, but picture the situation that I buy one item per month for 6 or 7 months @ 50 cents a go, but due to randomness I am included in the 95% of those tokens that are thrown away. Then on the 8th month I get hit by a 10 dollar charge for something that should cost 50 cents, and even assuming I remember I have had 7 freebies, I am still out of pocket. This means I have to keeping buying, and hope that I can get 10 dollars worth of stuff, and then get out before I get hit again for another $10. This then leads to abuse/gambling, how much stuff can I get without getting charged and then get out or quit?
Or am I missing something?
--My sig is bigger than your sig--
this looks like hidden advertising to me but i won't argue that point....
and it's based on 'patent pending technology' that is somehow acceptable by slashdotters (see here for more info)
this sounds like a lot of marketing hype. why not just have a company that processes micropayments in mass -- if i buy 10 songs for $1.00 each from 10 record labels during 3 months i should be charged $10 as soon as it is profitable to charge me, possibly at the end of the three months, possibly after my tab is at $5.00. i think this is basically what happens with peppercoin but in a more complex, mathematically obtuse way.
finally, what's up with all the hot women on the peppercoin page? it's like i'm supposed to be able to buy them with peppercoins.
fear is the mind killer
The impression I get is that this is effectively PayPal. The user loads, say, $10 into their account via a credit card. Pepper coin then pay the transaction fee (maybe $.25 or something).
Then basically Pepercoin, I assume, keeps a tally of how many items a given site sells. On every N-th transaction, they hand over $N to the retailer. This way the retailer only effectively needs to pay the $.25 (+ Pepercoin's markup of course) per 20 transactions of whatever.
So, to sum up, this seems basically like Paypal but reworded. You still can't use your credit card to make micropayments and you still need to have an account with Pepercoin, and for the retailer to accept Pepercoin, before you can make a transaction.
Unless I'm missing something this seems pretty useless. I thought the major factor with services with Paypal etc. was that users don't want to have to sign up with a 3rd party - it's just too much hassel.
Nice solution, Ron.
Can I throw away some 5%-10% less invoices?
And by the way, Your Telco has a micropayment solution since ages. Your Mobile Operator also.
It's called phone bill.
Don't know were I read it several years ago:
"The (Business) Model of a (3G) Operator is the Business Model of a bank"
chess
Okay.. from the merchant's side.. he does not wanna mess with trying to account for a 5 cent sale.. so lets calculate the a 0.005 probability ( thats 5 cents out of 10 dollars ) and assign that probability to a ten dollar token, that the token is any good. So, in effect, the merchant is gambling he is going to get paid - in this case, for the sum of 5 cents, he accepts a 0.005 probability he gets $10. Basically, its just like gambling, where PepperCoin is the "house". But over millions of transactions, statistics would approximate the same return to the merchant as if he tallied all the micropayments.. but the merchant does not have to worry with millions of tiny payments, he works with thousands of larger consistent payments. And is willing to accept the accounting simplicity as tradeoff against any probability error, as well as the overhead of the "house cut". This technique allows the processing of billions of payments without keeping detailed records on each... the only thing going through is the statistical averages of who gets paid what.
Well anyway, thats my *understanding* of how this thing works...
One neat thing is that it appears any identifying information to the purchaser would be lost in the "noise". comments invited.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
I have only read it quickly, but there seems to be no mention of the way PepperCoin will charge the customers. Since the PepperCoins' value is transferred from PepperCoin to the merchant and this transaction is "optimized", the other transaction (PepperCoin <=> customer) is important. It seems to me that this would only(?) work with a pre-paid amount (otherwise the customer would have to purchase frequently enough to be charged for several transactions at once), so the claim from the article: Letting consumers buy hit music recordings for a buck or less, without charging $10 a month in subscription fees, could be just the thing to ignite the micropayment market. is questionable.
"I love my job, but I hate talking to people like you" (Freddie Mercury)
What about the retailer that doesn't do a heavy volume of business through PepperCoin?
For example, if it's a 50/50 probability that a given coin is worth High or Low and you flip that coin 100,000 times, then within a minimal error, the coin will be 50,000 High/50,000 Low. But what about a retailer that only does 1000 or 500 or *less* per month.
Then, add on the fact that the PepperCoins being discussed aren't necessarily 50/50 but sound more like 5/95 or 1/99. If you closely examine any 500 of those 100,000 tosses earlier, you can probably find quite a few runs of 500 lows or more in a row. Suddenly, there are whole months that a retailer is going without payment to wait for that one time when they get compensated waaaay down the line. It seems a feast-or-famine proposal for the smaller retailer.
Mordor...a magical, mythical land where women are more rare than dragons--but where every man would rather find a dragon
"I thought the major factor with services with Paypal etc. was that users don't want to have to sign up with a 3rd party - it's just too much hassel." You are already dealing with a 3rd party.. the Credit Card company; only you don't notice 95% of the times.
If Peppercoin succeeds in making themselves perceived as "transparent" to users, they could be succesful. Anyway, I guess that if micropayments becomes a rich business, Credit Cards companies will take the business in their hands.
This message doesn't need a sig
After reviewing the FAQs on the Peppercoin site, it appears that the consumer will always be charged the 50 cents -- never the '$10'.
From what I can tell, what Peppercoin does is batch the transactions so that the total of all of them goes into *their* merchant account. I couldn't find out any info on how often they would distribute the funds to member merchants, but I'm sure the frequency of payments (triggered by number of total transactions or dollar amount) would be tied to merchant membership fees.
Just my $0.02US
Only a certain number of customers will reach this break-even in a given time-period.
The value of a "winning" Peppercoin to a merchant would be this break-even amount, minus the credit card company fees and Peppercoin fees.
The odds of a merchant getting a valid Peppercoin would be based upon the number of break-even transactions made in say, a month.
If 10,000 total transactions were made in the first month, and only 100 people spent more than the break-even amount, say $12.50, the odds of a given coin being worth $10 would be 1/100.
It's a novel system, as previous efforts to deliver microcash required customers to buy tokens in advance. This system places the risk upon the merchants, who are being asked to gamble that people will use Peppercoins on a regular basis.
As a system like this matures, it could actually work, maybe.
I think if you randomize you will get a chance to fudge some data; I mean, if in the end your average price of item turns out to be like 49.68 cents averaged over long term, you will have a very unlikely chance of noticing this discrepency. especially most (ALL?) financial software rounds to the cent.
At the same time, the above is assuming that EVERYTHING is 50 cents. Now, imaging there are things costing different amounts of money, and calculating if papercoin is ripping you off that 0.3% becomes difficult if not impossible.
Now, of course, I can't quite figure out how does papercoin charges the consumer. That's really weird because THEY can't be hit with the 25c charge everytime either or they will go under; so they will either have to
1) act like a bank / paypal and have you keep a balance.
2) wait until your "sum" is large enough and charge it all at once.
both have serious problem.
Of course - this entire thing is really a credit card system problem, that can really only be solved by the credit card companies - but they seem to have no incentive to do so, so... we might be stuck here for a while.
My life in the land of the rising sun.
No, the customer get's charged.
But the term lottery is very good in this context. Let's look at the scheme from that point:
If a state organizes a lottery (at least here in Germany) it is obliged to pay out at least 50% of the money that came in from selling the lottery tickets. This payment occurs in the same random fashion like the pepper coins.
In reverse, a customer of a lottery can roughly except to win back about 50% percent of what he shells out (it depends on the time frame and how all the win money is distributed among different winning ranks).
The same holds for the merchants participating in that peppercoin scheme. Statistics is on their side. The more transactions, the smaller the error margins.
I would call the scheme a reverse lottery.
The critical point is of course the tuning of the propabilities in the win/loss one time pads that Rivest's company is likely to distribute to the client software. He can make money by having to low win probabilities.
As a participating merchant I would perhaps insist on a contractual margin - if I have N zillion transactions there should be guarantieed error margin. If my pepper coins are below that margin, I should get compensated by Rivests company, if I'm above I should pay back.
The general idea, to use statistics to neglect expensive detail, seems very good to me.
Regards,
Marc
Let's say you're a firm hoping to make $10,000 in sales in the next month, corresponding to 20,000 Peppercoins. Each peppercoin corresponds to a random variable which is $10 with probability 0.05
Your expected income is in fact $10000 while your standard deviation is 10(20000*.05*.95)^(1/2)=$308 or so. So while the variation is painful, it actually turns out you'll be in the $9000-$11000 range 99% of the time.
Similarly, if you scale down by a factor of 10, so you have 2,000 coins. Your expected income is $1000 while the S.D. is 10(2000*.05*.95)^(1/2)=about $100 or so. The 95% range here would be from $800-$1200, which is more painful but still managable.
The odds of a run of 500 lows in a row is about 7.27*10^-12, safely ignorable
Quote: "Just my $0.02US"
Is that in peppercoins, or real payment?
For the user, sign up for a PepperCoin account, providing your credit card number, and when you want to make a purchase:
The token is a digitally signed token with the merchants "name," the consumer's "name," the amount of the transaction, and a value of either $0 or $10 (to the merchant.) Your PepperCoin account is charged $0.50.
The merchant, upon receiving a token, sends you the product, and if the token is worth $10, keeps it for later.
At the end of the [day / week / month / quarter] send all the $10 tokens to PepperCoin. PepperCoin sends back the money for the total value of the tokens. What you'll find is that (money received) / (total number of tokens collected) is $0.50. The merchant will be charged a fee for the service, so you might see something like $0.45 per purchase (10% fee.)
Back to the consumer ... over time you'll accumulate $10 or more in purchases at which point your credit card will be charged. If, let's say, 6 months elapse, and you still haven't accumulated $10, you'll be charged your current balance.
See ... PepperCoin makes about 10% of all the purchases minus the cost of credit card transactions to the consumers (about 5%), the merchant gets $0.45 instead of $0.20 on a $0.50 purchase, and the consumer is charged dollar-for-dollar what they spent.
--- Jason Olshefsky
Karma: Poser (mostly affected by adding this line long after everyone else did)
Peppercoin will not pay the merchants 100% of the money that they took from customers.
It will pay out 100% minus the fee for the real transaction costs minus a win margin for them.
The benefit is, that if e.g. only 5% of the transactions will result in a credit card fee, this scheme gives a 95% cost reduction in real transfer fees - a big big improvement.
Ok, the merchant needs many transactions to get reasonable statistical error margins. But like with insurances on could imagine different peppercoin fees for different risk levels.
The scheme is elegant, but it makes peppercoin a mix of a bank and a lottery, areas typically keen defended by state monopolies. So guess it will be more a legal/political issue than a technical/economic one.
Regards,
Marc
... it's the credit card company charging so much per transaction. Why work around that problem?
The "market" for credit cards is skewed because the transaction charge is applied to the merchant rather than the purchaser. If the charge did come direct from the purchaser, the purchaser would choose a credit card that offered the lowest charge. As it is, the merchant has no choice (other than saying "I don't accept Amex), so competitive pressures don't apply.
Peppercoin-type operations will further mask the skewed market - we will all end up worse off; except of course for the Visas and MasterCards of this world.
Rob.
what's up with all the hot women on the peppercoin page? it's like i'm supposed to be able to buy them with peppercoins.
you mean like this one?
or a little buddha-devil maybe?
i get the feeling both merchants and consumers are going to root around in the hype for a while and then just turn their backs on this.
slashdotters will hate them anyway because they obviously use windows in the office.
This Like That - fun with words!
Seriously, there are protocols for coin tossing etc such that you don't actually have to rely on trust and neither party can cheat. A quick description:
:)
- Alice sends the encrypted result of a coin toss
- Bob sends the answer they're hoping for encrypted
- Alice sends Bob the key that was used to encrypt the toss result. Bob sends the key that was used to encrypt his bet.
(note: both messages are send with some kind of pre-agreed nonce)
Neither party can cheat... theoretically.
You can. Just append the text "and apparatus" after the writeup of your algorithm. You haven't quite patented the alg itself, but you do have rights to any machine running it, which is just as good.
My guess is this system was likely not designed for use by run-of-the-mill merchants with transaction volume below the millions (and conceivably billions). Like many have pointed out, your typical store merchant would laugh at the prospect of roulette-based revenue.
This system was designed to solve the problem of handling billing and payment collection for A LOT of transactions per unit time. Think NASDAQ. Think VisaNet. Think McDonald's-years. Think pay per wireless packet, a concept routinely floated by Rivest's MIT colleagues including Dr. David Clark.
Coupled with a computationally efficient token verification scheme, I could see how this system could turn standard billing practice/procedures on its head, provided the big corporations have enough smart people in their stables to say, "Rivest is right." For instance, if my statistics memory serves, this system should effectively enable stepless billing (without increments or round-off issues) - in other words, finest-grain discrete-time pro-rating for services provided, tunable per application to some arbitrary epsilon.
I think music downloads are a red herring. It's entirely possible that PepperCoin will never see the light of day as a consumer payment service. But I'm very curious to see what the world's largest accounts receivable departments have to say about it.
E-gold or Goldmoney are payment systems based on transfers of ownership of real physical gold, denominated by mass. Goldmoney scales down to 0.001g (which is worth just over one US cent at todays wartime-high gold prices) and all the way up to infinity. E-gold scales up likewise to infinity and down further (to about 4/100 of a cent at todays prices), and has an e-silver version if you want to go yet smaller.
Why stop with randomizing individual transactions?
Why not just randomize *all* payments for a particular supplier? Either they get paid by Peppercoin that month, or not. Better yet, Peppercoin can randomize their entire set of payments. Either: "Hooray! Peppercoin paid all its bills this year!" or "Sorry. We went bankrupt."
Until I see otherwise, I expect the latter.
J'aime mieux les méchants que les imbéciles, parce qu'ils se reposent. -- Alexandre Dumas
BUT, not anytime soon, and you've identified the exact reason why: peppercoin patent monopoly. No reasonable merchant nor consumer should bet on a scheme that locks you into one vendor, especially for something as vital as your very revenue source. We like money because it is 100% transferable -- I can get it from anyone willing to trade with me. Credit cards are also competitive -- if I don't like Visa, I can try AmEx or Discover or MasterCard, and most vendor's have a single machine that can take any of the above. If I don't like peppercoin, there's no alternative I can switch out for -- the system is closed, patented, and sealed. Sure, there are other micropayment schemes that have lived and died, but if I wanted to start a peppercoin-compatible service, tough luck; it'll be at least 17 years before we get a legal shot at that.
As I see it, the biggest problem in micropayment is the large amout of time each user has to spend by deciding if a certain page is worth clicking, and the technical means that require plugins or other stuff. I highly suggest everybody to read Clay Shirky's The Case Against Micropayments for more infos about the problems micropayments have today.
After researching past failed efforts for a business plan competition, I came to the conclusion that the problem with Micropayments has never been the technology or payment method behind them. There have actually been multiple plans that did just fine in those areas.
The failure is summed in one word, MOMENTUM. Micropayment companies can't get any because they usually sign up one or two bigger names (those sites have to have *really* compelling content for anyone to sign up), people go elsewhere when they see their favorite little diversion now requires payment, and the micropayment start-up runs out of money before they get momentum. In addition to that, people prefer subscriptions to micropayments.
I do think there is a way to solve the problem, but Peppercoin doesn't seem to be it.
Boom Shanka
Visa/MC competitive?
Courts will ultimately decide this one:
antitrust suit info
Explain to me, o banks, why it costs you $2 to give me money from my own accout? Why it costs you $10 to wire transfer some money from one account to the other? Why it costs $1 to give me a balance statement? Why it's 75c to use your ATM card at anywhere but a supermarket? These are just the costs for consumer-visible transactions; the costs of using a credit card or ATM to the business owner must be similarly padded.
These are database transactions. They happen almost instantly and they consume resources at a tiny fraction of the cost we're being charged. It's electricity being sent over a wire; the marginal cost is so close to zero you need calculus to describe it. This is why micropayments don't work yet, and elaborate schemes like this randomization are even necessary at all. PayPal and similar systems have eliminated these costs, but "real" banks refuse to, because they make an assload of money off of charging for the movement of electrons.
It's rare that you're presented with a knob whose only two positions are Make History and Flee Your Glorious Destiny.
There are issues of user approval that need to be solved to get this working and Peppercoin (man what a lousy name) is not even close to any of them.
I'm not gonna waste your time with my words since Clay already wrote about it in The Case Against Micropayments
The main problem is that users hate micropayments:
"Why does it matter that users hate micropayments? Because users are the ones with the money, and micropayments do not take user preferences into account.
In particular, users want predictable and simple pricing. Micropayments, meanwhile, waste the users' mental effort in order to conserve cheap resources, by creating many tiny, unpredictable transactions. Micropayments thus create in the mind of the user both anxiety and confusion, characteristics that users have not heretofore been known to actively seek out."
Go ahead and read the article. It explains the problem in better detail and it clearly shows why the problem is conceptual and not technical. Then you can happily get on with your life, without Peppercoin and without micropayments. Cheers.
There are two problems with micro payments: 1) The processing cost of the seller. This solves that problem. 2) The decision cost of the buyer. When buying online you are buying sight unseen. low cost items are generally impulse buys, which tend not to happen sight unseen. It also makes a LOT more sense to sign up with a single specific trusted company for sight unseen stuff then to purchase from tons of others.
excitingthingstodo.blogspot.com
Implemented ages ago, in the public domain.
Monte Carlo pledge fulfillment for the Buskpay microdonation system.