I decided to turn off anonymous comments on my blog. A few comments on my "I love Apple" post were made anonymously, and those comments tended to be more provocative or downright cranky. While I wanted to post at least one of them, I didn't feel it was right to post inflammatory content that had no author to respond to.
I do moderate my comments, trying to stop spam first and foremost, and really inflammatory comments second. If the comment has an author, I'll rarely not post a comment. I post if I don't agree with the comment just as long as it is thoughtful and not mean.