RealGM

I'd be surprised if this one hadn't been thrown out before, but the ability to "delete" topics from your personal view could be a nifty little thing to add.
Would maybe want to add in something to query against the last activity in the post and delete entries that've been inactive for X months to keep DB storage down. Not sure what the global topic/user counts or storage contraints are.

I think it can be useful sometimes to look through old posts, so I would be opposed to automatically archiving them.