Appear Offline
You cannot see other players as well as other players not being able to see you whether that be on friends list/team list/chats/game world etc...
GM's and all those other mod type ppls will still be able to see you though.
You can create exceptions to who can see you allowing friends or teamies to see you and chat to you etc.
Another option can be selecting an area on the ground (click and drag box type of thing) where you will be able to see and communicate with those people there in that area. (Can help to reduce lag during tournaments instead of changing channels)
Just a thought of how this can help :P