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Gran Turismo 5 Prologue, then Gran Turismo 5 itself when it comes out, Prologue will allow you extras in the main game as previous incarnations suggest. That's all I can think of really, as others have been mentioned.
 
Unless your into the RPG games I would get the Final fantasy game? I don't remember the title but I heard the graphics on the game is amazing :)
 
I would recommend you purchase Ratchet and Clank Future: Tools of Destruction. You might try renting Uncharted and Heavenly Sword to see if they are your type of game.

If you like FPS, Warhawk is awesome—especially since Insomniac continues to release expansion packs.

Also, I'm a big fan of social gaming. So SingStar and Buzz! Quiz TV are must-haves for parties.

As for the PSN, the only title I would really recommend is PixelJunk Monsters. If you have disposable income, you may want to try Flow, Super Rub-a-Dub, Echochrome, Elefunk, PixelJunk Eden and Racers. However, in my opinion those specific titles get old quickly.
 
small update

Well I bought GTA4 used off [H] forum for $30 Friday night, and last night I bought PixelJunk Eden, PixelJunk Monsters, and PAIN. I was strongly considering buying either The Last Guy or Bionic Commando: Rearmed in addition to the other 3, but I think I'll enjoy those 3 for the time being and buy those 2 others in a week or so.

I'm glad I took a gamble on PAIN, we've had a riot of a time with it. I wish they had a demo of it available, but I figured we'd like it and thankfully, we have. I went used game shopping Friday night and came home empty handed; there were several games I wanted but just wasn't happy with what Gamestop or the mom-and-pop type store down the street wanted for them.

Next buys -
-Mercenaries 2 (can't wait)
-LBP (need to preorder to get the Kratos outfit :D)
-Warhawk (based off 2ny/sikki's love of the game)
-Ratchet & Clank F:ToD (can't wait)
-Heavenly Sword
-Uncharted
-Resistance: FoM
-MGS4
-The Last Guy
-BC:R
-MK II (maybe :))

Need to pick up a pair of DS3's as well. ;)
 
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