I was thinking, maybe certain sections could be locked for users that aren't in a specific user group. Example, I want to sell an account, but ONLY want it to be open to people in my group, so I could post it under a "Ghoul" subforum, and anyone not in the group wouldn't be able to access the subforum. I thought this would be nice, but ya thanks.
This is already possible, group owners may contact a forum administrator to add sub-forums and even change permissions for them. (Just please don't request too much if you ask me...)