I know others have mentioned custom avatars, I think that would be nice.

One thing that I have noticed is that the forums don't track the threads you've read correctly. I have to enter and exit every thread twice for it to register that I've read it (doesn't matter if I refresh the page or not). And sometimes it marks things as read when I haven't read them, so when I click "View First Unread" it skips past stuff, or entire threads are marked as read when that's not the case. I am a regular on a couple other forums too and I haven't noticed this behavior anywhere else, so I assume it must have something to do with the vBulletin software.