Tim Tucker posted an interesting solution to some of the CAPTCHA solving stuff going around. He posted that to comment on his blog you must enter any data, as long as it’s incorrect. So as long as you don’t type in whatever you see and it is six characters long, it will be solved.
As the posted noted, this isn’t particularly good security, as a) it can be broken by anyone who views the site and knows that rule (therefore it’s not good against targeted attacks), and b) if it ever gains popularity it will become standard in splogging software. Still, it’s an interesting take on the same old problem of blog spam.