reCAPTCHA

A new CAPCHTA (for Completely Automated Turing Test To Tell Computers and Humans Apart)program from Carnegie Mellon University is stopping comment spam and protecting passwords with a twist. reCAPTCHA takes text from scanned books and uses your human eye to convert it to editable text. With 60 million people using a CAPTCHA a day, books can be digitized far quicker and at a tenth of the cost.