[@Mahz], I have a small idea, I dunno if it has been suggested before.

It would be great if there was an option to disallow players from posting in the IC until the GM / Co-GM(s) grant them access. Of course, this would be an option, able to be disabled/enabled. This would be handy for preventing random players popping in RPs, and would also be handy before the RP is to start; I've occasionally seen RPers that can't contain their excitement and just start the IC on their own. It would also be handy for private RPs.