There's a Might and Magic: Dark Messiah Multiplayer Open Beta available through Gamespot and Steam.
http://www.gamespot.com/betas/darkmessiah/index.php
Just need to have an account at Gamespot to get a key, and have steam to download and play the game. I must say it's really fun =)
Oh yes, and
Tremulous. Both are FPS, but Dark Messiah is like... medieval fantasy (Swords, Magic, Bow, etc.) Been awhile since I've played Tremulous, honestly. While I'm at it, there's
Natural Selection, a mod for Half-Life.. Natural Selection and Tremulous are very similar.