My friends and I are looking for a good 3 or 4 person co op game.

Like Borderland or L4D2. Those are our current games along with Halo 3 and Modern Warfare 2. Any other good games out there?

If your into co op games, try out Gears of War 2.

-Halo 3 -Halo: ODST (Buying it new gets a new Halo: Reach beta key? Not 100% sure) -Borderlands (Didn't like the game personally but received 8.5 rating on Gamespot Review) -Battlefield: Bad Company 2 Halo 3, but Halo: ODST has firefight mode, a coop gamemode where you survive waves of enemies. Not sure but ODST is supposed to give you a beta key for Halo: Reach (2 games in one.) Borderlands is relatively good but I never really took to that game. Haven't played it in months after my first playthrough. Bad Company 2 is also VERY FUN to play with a group of 3-4 friends. You can literally form a squad with your friends and fight alongside them.Sinful_Merc

This and the Horde mode in Gears of War 2.