I'd recommend you various games:
Call of Duty Black Ops is a very interesting and good shooter game published by Activision.
Battlefield 3 if you don't like Black Ops, be aware that not everyone is able to establish connection with the EA servers tough.
Playstation Home: Free to download for any PSN-User, socialize and interact with your friends, clanmembers on Home and establish your own life in Home.
Assassin's Creed: Brotherhood : Game with a historical setting in the Renaissance, Italy ca. 1500. Multiplayer mode comes along with the storyline and is an awesome addition to the actual game, very interesting to play.