I'd like to create an RSS feed forum where the default RSS feed will post threads but the threads and posts in that forum do not count towards site/user totals.
Also I'd like to have the option where if any of the threads created by the RSS Feed receive a reply from a user/member then that thread is automatically moved to 'forum x' and becomes a part of the discussion.
For the first point, a suggestion has already been made to be able to exclude certain forums from post count, etc.
For the second point, you would probably be better off asking in the add-on requests forum.
This is quite specific functionality which probably won't be that widely required, so the chances of it being included in the core are quite low.