We've had captcha support for some time in CiviCRM. This is not a very popular feature since getting it to work properly is not trivial (you need the right PHP libraries and the path to the a ttf font on your server)
This post by Gordon Heydon, pushed me to investigate ReCAPTCHA, which has a cool tagline: Stop Spam, Read Books. I've seen a few sites in the recent past that have been powered by ReCAPTCHA.
This seems something cool, gives us integration with yet another web service (oh what... Read more