The only anti-spam software I use on my blog is Bad Behavior. That plus comment moderation has been sufficient for me for quite some time. I have qualms about both akismet and Spam Karma 2, and as such prefer not to use them.
Since upgrading to WordPress 2.0, I've been suffering a significant increase in the number of spam comments sitting in my moderaiton queue. I sent my Bad Behavior log off to io_error, who confirmed that they were all manually entered, and as such slip past his plugin. Most of the spam comments have Asian text in the body, and a lot of them link to .cn domains. So my first line of defense was to add .cn to my list of forbidden words (with the unfortunate side effect that no one with a blog in China can comment here, for the time being). That didn't really do much to help, though.
Looking through the spam comments, almost all of them have an all-numeric username supplied. So I cooked up Non-Numeroc Names, a plugin which will flag as spam any comment submitted with an all-numeric username. So far, so good: all of the spam has been flagged as such, and diverted from my moderation queue!
Chris' Spam Nuker plugin makes it possible to retreive any legitimate comments that may have been misclassified. After that, you can eliminate all the spam from your database with a single click of the mouse!