I don't know. I'm waiting for someone with at least a +110 IQ to post their plan for an exclusive forums.
Bit to the rescue!
In my forum, there is a user hierarchy like so:
Nonmember (unregistered): Can only post in Off-Topic and other similar sections
Member: Gets rights to post everywhere except the Admin area (which is admin-only viewable too) and the Big House (back alleys of the forums where Spammers and total handicaps go, more on that in a bit)
Moderator: Gets a few more rights, can post in both the Big House and admin-only areas, and can overall moderate
Admin (me :P): Gets to post everywhere, ban people, do everything, of course.
Spammer, Troll, handicap/other: The can only post in the Back Alleys of the forums. This includes two sections: The big House, where people can talk about how they should be given back normal privileges or whatever, and the Back Alleys, where they can do whatever the hall they want. Topics older than two weeks are deleted, and admins frequently clean up. Of course, I enjoy this part of the administration process a bit more than most.
Honorary member: A member who either doesn't frequent the forums or isn't an admin, but who acts as a sort of lower-level moderator and a member who can post in the Back Alleys and overall help with the administrative process.
I can't get into more detail until I fix my forums, but the main idea behind this is that forumers without an ID can post in Off-Topic and a couple other parts like AoT forums, while Blockland Members can post in a slightly wider range of subjects and sections. Now that I've written that down, though, I'm not sure it would work very well without the addition of more sections.