I don't know if this has been covered yet, but here are a couple thoughts. If you click on a player's profile, how about showing if that player is already in a game. I got invited to play but was already playing , and it seems rude ignoring the invitee. Also if you do get invite and decline(already in a game), how about a response box explaining why they declined. Just trying to be nice here.
Thanks for listening,
Michael