Combat Arms

[rhonnin]

Free to play fps and pretty fun if a wee buggy, supports clans and has a pretty nice chat room/match making lobby set up reminiscent of Mplayer.
It promised a quarantine/zombie mode in the banner ad I clicked to get there but that aspect is pretty weak and poorly done. It has several server modes, elimination, quarantine, CTF, etc... and a rank system that unlocks weapons and other equipment as well as specializations. You earn money in matches to spend on weapons and upgrades like scopes and silencers or real world cash for a wide range of things. Servers load fast and were pretty lag free for the most part.
http://combatarms.nexon.net/default.aspx

[Gunther]

More killing zombies!! woo Hoo! When he ran out of ammo, I was like, oh noooes, hez gonna be da zombie 2., but then he pushed a button and everbody died. Go Killa! Go man, go!

[rhonnin]

Yea, the trailer is like a million times better than the actual zombie mode in the game.