[...] As you get the full range of permissions, you could easily prevent a user from posting anywhere, or prevent then from posting in a particular forum (or prevent them from viewing that forum), or even give someone access to download attachments in a forum when they normally couldn't.
I'm sure I've suggested this as well. Shouldn't really be too hard to do as an addon. Add a table to keep track of user_ids and thread ids and if user_id is listed against the thread_id, treat them as they have no rights in the particular forum.
Some may call it a fudge, but it would probably work!
Yes if you do not care about:
- Informing the user that they have been banned/unbanned (alert)
- What happens when threads are merged or deleted
- Option to view thread but not being able to post
- Removing the ban from the table upon user delete
- And so on...
Other than that, it's easy peasy.
EDIT: June 16, 2012
You may want to check out the Thread Ban add-on