The Unreal series of games is on offer at the moment on Steam, see this thread for more details...
http://forums.overclockers.co.uk/showthread.php?t=18055487

http://forums.overclockers.co.uk/showthread.php?t=18055487

if i go on it now i feel like i have to 'force' myself to play it, and sometimes i never even join a game before just quitting out again