I'd like you guys to list out all the features you use on the boards that you like and couldn't live without.
Also list some features you'd like to see us use that we aren't doing now.
Examples:
Font changes and simple html in posts: I change my font rarely, but I do use html for other things. I'm not sure what else I'd prefer since I always seem to make the options I have work for me. It wouldn't hurt to have the macro page more accessible.
Private messaging (any enhancements you'd like to see with that): Like others, I'd like to have the ability to see the message I'm replying to. We had this feature with the Fan Collective PM's and I'd really like to see something similar return to the board's PM. As it is now, I usually paste PMs sent to me into Notepad and type out my reply there. I don't use it enough to care about any other features. ;p
Spellchecker: Never use it. I either use Firefox's spellchecker or a dictionary.
User searching: I don't use it often, but I can see how it can be handy. Like on the regular search page, the score and average rating could go. While I'm on the topic of searching, it'd be nice if we could search the archives. I don't really care if they come back to the boards proper (I know where they are.), I would just like the ability to search them specifically. The search needs to be tweaked as well. "Second" is too common? I'd like that the "too common" is ignored when words are in quotes.
Avatars: I use 'em. I think a way to see them larger (such as hovering over them and they appear in a bubble at full size) in the selection area would be nice, though.
Signatures: No problem here. Would be nice if they were only allowed to be so big. I'm not a fan of allowing scroll-bars, but.. meh.
Subscriptions: Honestly don't use them. The thread indicators are enough for me to see where I've posted and I can always go back to see additional posts. Plus, I float/bookmark threads I haven't posted in, but want to keep up with. 
Ranks: Does it really matter if I like them or not? ;p
etc.
New things (things we don't use):
Post rating: This used to be a feature. I liked it and used it more than posting. I'm not sure it'd be a welcome "addition" to the community at present, though.
Tagging: Eh... I'm fine with the search.
Profile add-ons (whatever those might be): Too vague to truly comment on.
etc.