http://www.kongregate.com/games/lizzard4000/ratz-instagib This game is a great little DM, a lot of fun! We should have a tournament.
I haven't managed to get this one to install (due to desura being a bitch), but I think it would fit perfectly for the Empires community: http://www.moddb.com/games/transformice/videos
I was thinking Quake Live? (being the online one i played like twice and what they used to play at IEM)