Captchas help captcha

I just ran across this article in the on-line version of BBC News about Carnegie Mellon’s Captcha (Completely Automated Public Turing test to tell Computers and Humans Apart) application, which I have been a fan of—and using—for some time. But it wasn’t until reading the article that I realized that Professor von Ahn's little SPAM-fighter app was a contributor to one of my causes: digitizing historical texts. It also helped the native Guatemalan win a MacArthur Foundation Genius Grant in 2006.