Once a week we several of us pile in for a few hours of linux only gaming. We play any multiplayer game for linux, lately that's included Urban Terror, Blood Frontier, Teeworlds, Assault Cube, and a few lesser known games we can cram onto our servers.
Our normal game time is Sunday afternoon(3pm EST), but we always end up playing more through the week. Stop by and chat with us on IRC at #lxgc or irc.freenode.net - or http://lxgc.gwos.org
We call ourselves the Linux Gaming Cabal, and all linux gamers are invited to play and participate.
Hope to see some of you join the fragging!
PS: This sunday we are scheduling to play Warsow and Assaultcube.