Ok so I’d heard of ReCAPTCHA but I didn’t really get it until listening to this podcast from the Museum of Science http://www.mos.org/events_activities/podcasts&d=1813
It explains ReCAPTCHA and how you can use them – I’m using it to hide my email on webpages. On the right side of this page under Please Join Us – you will see the link to the ReCAPTCHA hiding my email from all those nasty spammers and helping to digitize text!
Want to hide your email address? Get the code here http://mailhide.recaptcha.net/