I was poking around mail() functions for the researcher authentication system when I discovered reCaptcha. It’s run by a lab at Carnegie Melon. In a nutshell it reads books and when it hits a word it can’t understand, it sends in it as a CAPTCHA [those forms that determine if you're human].
About 60 million CAPTCHAs [aprogram that can tell whether a user is human or robot] aresolved by humans around the world every day. In each case, roughly ten seconds of human time are being spent. Individually, that’s not a lot of time, but in aggregate these little puzzles consume more than 150,000 hours of work each day. What if we could make positive use of this human effort? reCAPTCHA does exactly that by channeling the effort spent solving CAPTCHAs online into “reading” books.
reCAPTCHA improves the process of digitizing books by sending words that cannot be read by computers to the Web in the form of CAPTCHAs for humans to decipher. More specifically, each word that cannot be read correctly by OCR is placed on an image and used as a CAPTCHA. This is possible because most OCR programs alert you when a word cannot be read correctly.
That’s a win-win for me.
Posted by studybob 
Posted by studybob 