Oh man we're on the same boat then, cause I'm thinking of buying a PS3. I have a list of games I'm gonna buy rofl... They're supposed to be good games.
inFamous Modern Warfare 2 The Uncharted games Skate 2 Little Big Planet
I hear that Metal Gear Solid 4 is a must get for PS3 owners. You should get that.
The best RPG game on the PS3 has to be Valkyria Chronicles. Awesome graphics, awesome story, awesome strategy. It has to be the most underrated game on the PS3.
It really depends on your interests, but I'll suggest the ones I enjoyed the most: -Prototype -The Last Guardian -Metal Gear Solid 4
Those are the ones that really stick out in my mind. Plus Arkham Asylum comes out at the end of this month, and PS3 owners of the game will get to play The Joker and several challenge maps (maybe that's just interesting for me though).
Metal Gear Solid 4 Uncharted COD4 Red Faction: Guerrilla Midnight Club LA Little Big Planet Skate 2
There's a good list to start with when buying games. These are many of my personal favorites, will give you a wide variety of genres, and have plenty of replay value, unlike some games like inFamous (done after 15-20 hours total, need to get rid of now).