Thanks for saying what types of games you like, really helps. Little Big Planet is good for almost any gamer, but the 2nd is coming out and you may want to wait. FPS: COD/BattleField 3rd: NOT SOCOM... uncharted 2 is a good adventure game, the 2nd is better than the 1st.
Red Dead Redemption is great. They're gonna release DLC with zombies. Also, if you don't have it for another console, I'd recommend Dragon Age: Origins. Playing through the story took about 30 hours for me the first time, and it's fun enough to play again. It's gonna kill plenty of hours.
Metal Gear Solid 4 is one of the best games for the PS3. Every aspect of the game from the graphics, to storyline is fantastic. I can't wait for the 5th one with Raiden to come out....
fallout 3, grand tourismo 5, assassins creed series, little big planet 1 and 2, god of war 3, the elder scrolls oblivion, ya thoses are my favorite ps3 games.