I use Akismtet and AntiSpamBee on myblog, and was still getting spam. This basically got rid of everything.
There's a hell of a lot of these, but after trying most of them, I still think that this is the best anti-spam plug-in you can get, for the following reasons:
1) It's incredibly effective - it picks up virtually all machine generated spam (which is more than 99% of it).
2) It picks up virtually all trackback spam too.
4) it's totally transparent to the commenter, and it's simple and easy to configure too.
Really helps me decide what comments to ditch.