2 suggestions in 1
1. Possibly make a "tag" for threads.
So in this section it could have a "tag" before that displays like "[Suggestion]". Market place could have [Auction], [Buy], [Sell]. Maybe even something to show at a quick glance that "Hey look X thread is in a sub forum." (like have [Food] Thread Name... probably a bad example but you probably can understand what I mean.)
These tags would be optional and would basically be a new Menu field before the Title Text input.
2. This is more of a "personal" suggestion but I could see where others might use it.
Something that "subscribes you" to different events... Such as SoTW, GST, etc. Gives you up to date notices saying that X voting is open or Y event has started. Maybe even if its starting an event it basically PM's the thread to people on the list. Or event an update on a game such as a maintenance or new patch info.
It would be subscription based so only people who would like it will get PM'd. Maybe even as a trial feature to see how popular it would be.
Theres something sort of like htis for thread subscriptions, but this basically gets new threads and PM's them to you.