Yeah, the problem with most captchas is that they're visual and they're working in an area where computers are starting to get really good. The main thing that computers are still pretty bad at is understanding completely arbitrary text, so the way to go has to be in that direction (which also has the benefit of being handicap-accessible). Ask questions, in text, that have textual answers. Throw in a random-number generator so that the questions aren't just a memorisable list. And most important, make EVERY USER of the captcha system ("user" here meaning the owner of the blog or the site, not the visitor to the site) able to edit the question list. Any system that is uniform across all its users will become a target for spam-hackers to break. But if you can change the question? Maybe even just _rephrase_ the question? Way, way harder. People are still smarter than computers, we just have to give them the chance to actually do their thing.<p>I wrote a plugin years ago for MovableType as a proof of concept (which I still use on my own blog): <a href="http://www.blahedo.org/botblock/" rel="nofollow">http://www.blahedo.org/botblock/</a> Even a user that doesn't want to touch any of the code (even though it's pretty easy) can always edit "Add one to this number:" to "What number comes after this number:" or somesuch. To solve the "more humans on this end" problem, it seems like you have to let them modify the very questions themselves.