I've been having some problems with spam getting in thru the comments on my wordpress blog. I tried a couple CAPTCAH tools but they didn't work. (I didn't have a chance to dig in and figure out why.) The recent versions of Wordpress come with a plug-in that's pre-installed called Akismet. Basically, when you turn it on, it compares incoming comments on your blog with those that other users have flagged as Spam. If it matches, the comment gets put in a holding cell. You need to regeister a username/password on wordpress.org to use it, but that's not big deal. So far, it works great. I just installed it the other day and it's already caught 11. Because it gets input from users of the tool, it should update pretty quickly to any new spam. So far, so good.