Only about 50% of the available address space is currently allocated, so theres still a long way to go. Here is a paste from the daily BGP report sent out by APNIC:
Routing Table Report 17 Apr, 2001
Analysis Summary
Number of addresses announced to Internet: 1238211568
Equivalent to 73/8s, 205/16s and 155/24s
Percentage of available address space announced: 33.4
Percentage of allocated address space announced: 65.5
Percentage of available address space allocated: 51.0
Slashdot Mirror
Something like this has helped on some of my sites as well, you can use something on-topic to the site, for example a site about bananas might have:
What is this site about? B _ _ _ _ _ _ (fill in the missing letters)
The spam bots have already beaten phpbb captchas, plus they sometimes even use a real email-address so email validation is no use either!
Only about 50% of the available address space is currently allocated, so theres still a long way to go. Here is a paste from the daily BGP report sent out by APNIC:
/8s, 205 /16s and 155 /24s
Routing Table Report 17 Apr, 2001
Analysis Summary
Number of addresses announced to Internet: 1238211568
Equivalent to 73
Percentage of available address space announced: 33.4
Percentage of allocated address space announced: 65.5
Percentage of available address space allocated: 51.0