Well, thanks to the generous wonderfulness of the WordPress community I now have my pick of ways of dealing with WP comment spam, and so do you :O)
The WordPress Combat Comment Spam is something that I think we now need for wikis and is FULL to the brim of fantastic solutions. So so so good!
I’m thinking about the comment killer:
“This is strictly weapons grade plutonium of the comment spam world. If a comment is flagged for moderation, it will be deleted if this plugin is active. So if you use it make sure that you have your settings properly adjusted. Oh, and if you have the “User must fill out name and email” box ticked, incoming trackbacks will be deleted too!”
“When a comment is posted to your site that gets moderated (because it’s caught by the spam words list, or has too many links, or for whatever reason), the author is taken to page where they can pay you to post their “advertisement.””