I’ve helped a few folks out with WordPress spam, and had started writing a quick and dirty FAQ on how to set it up (I’ve had close to zero spam since implementing my fixes). I was trolling the WordPress support forums, and there is a decent third-party overview of fighting comment spam on sites powered by WordPress.
The list is fairly comprehensive, but there’s not a lot in the “How do I?” category, so you’ll have to do a bit of reading to make things work. For anyone that’s hosted on deadsquid and reading this, you can ping me if you need some help.
If you run WordPress, haven’t put any blacklisting in place, and are sick of texas holdem and online poker comment spams, have a look.