Defeating Captcha
An anonymous reader pointed us at PWNtcha, a package that breaks various on-line captcha algorithms. The site provides numerous examples of easy (Paypal, and an older version of Slashdot make the list) and hard Captcha. It also links various sources explaining why Captcha is a bad idea.
A while ago, I remember hearing about how some spammers whould post the Yahoo Mail (or other free email services) Captchas on the registration forms on pr0n sites. The pr0n registrants would have to fill out the Captcha, but this would then be used by the spammer to get around the Captcha without any fancy software.