Comment Site-specifc Q&A, in CAPTCHA form, might work (Score 2, Interesting) 408
It seems to me that Q&A is the answer, if done properly. The key is to ask something that can only be answered if you're on the site. For example: "Next to the Slashdot logo at the top-left of the page, there is a five-word phrase. What is the second word in that phrase?"
You'd obviously need to change it up fairly often (and large sites would have problems still), but spammers would have a difficult time keeping track of answers for thousands of sites.
To make it even better, have it rotate through a few similar questions for your site, and have the questions be buried CAPTCHA-style in an image.
All told, it would seem to help. They'd have to resolve a very long CAPTCHA (117 characters in my example above) AND be on the site to get the answer. Seems like it would help.
You'd obviously need to change it up fairly often (and large sites would have problems still), but spammers would have a difficult time keeping track of answers for thousands of sites.
To make it even better, have it rotate through a few similar questions for your site, and have the questions be buried CAPTCHA-style in an image.
All told, it would seem to help. They'd have to resolve a very long CAPTCHA (117 characters in my example above) AND be on the site to get the answer. Seems like it would help.
