F.E.A.R. one of the top PC shooters, has just released a free multiplayer version of the game.  It's free to download- 2 warnings though, it's a huge 1.7 gb download, and you'll need a nice system to run it smooth.  
No review yet, I'm downloading it now, but the original game was rated one of the best of '05.

More info-  [url]http://www.gamespot.com/pc/action/fearcombat/index.html[/url]

A good place to download from- [url]http://www.gamershell.com/download_15038.shtml[/url]