I recently had to disable the complete comment section on my sites pages and then also force people to register to post on my blog because of so much spam. And I did look into some of these types of scripts (mostly server side stuff though) and it seems there is no all round solution and can be termed accessible but which also prevents the most intelligent spam bots from beating it.
louie that seems like a bad solution to me. Perhaps if it was capcha and then a sound for deaf people this might help, I don't know. Perhaps firefox and internet explorer should be the ones looking for a solution on this. Like I mean a central set of rules where the browser actually wont allow a POST to go through if a form has certain words, X amount of hyerlinks etc.