Breaking Captchas with humans

“We’re all familiar with CAPTCHA right? That impenetrable fortress of crazy squiggly characters that only a real human can decipher. Whilst they tend to drive us a bit nuts, they do actually provide a valuable function in that they prevent the automation of requests against online services.”
Troy Hunt

read more here: http://www.troyhunt.com/2012/01/breaking-captcha-with-automated-humans.html