I've had enough of comment spam. Therefore I started looking for a good solution and found the "AuthImage":http://www.gudlyf.com/index.php?p=376 plugin for "WordPress":http://www.wordpress.org. I installed it here and on a couple of other weblogs and it seems to work. What the plugin does is add a field to the comment posting form. It asks the user to retype the code that is shown in the image in an input field. This is not much work for the user, however makes it a whole lot harder for bots to successfully post their spam. If the code doesn't match, the comment is denied.
Now all we have to solve in trackback spam. Luckily I don't get that much of that (yet).