Oops. I found that my comment moderation filter picked up a lot of unapproved comments from readers, but didn't necessarily e-mail me the comments. So a bunch of good points from readers didn't get posted.
I need the comment filter to keep spam off the blog (there's tons of it), but I don't like it when your input gets lost. If you've left a comment that never showed up, check again. I think I've got them all.