In the last week or so, my comment spams have gone down from nearly 400 every few days to a few dozen. I think that turning on the comment moderation is working.
In the meantime, I’m always interested in what others have done to take control of their comment spam. Buzz Marketing turned on a feature that creates random trackback URLs. I hope that works for them. I will continue moderating comments, since it seems to be effective for my blogs.