Something that would be fun for the forums would be if each user could have a selection of alternate avatars that could be associated with the message. Everyone could have a "happy" one, a "sad" one, a "frowny face", or whatever. When entering a forum message, you could adjust the avatar that gets displayed with that message, as an option over the standard avatar. Might be fun for leaving comments, too.

There'd have to be an avatar ID tagged to each message, but it could be a small "slot" number, and everybody could have a limit of, say, six each.

I think it would make reading posts with lots of replies especially entertaining.