My own collection:
- Katamari Forever; loving it to death.
- Uncharted 1 and 2; also loving it to death, 2's multiplayer is an absolute blast.
- Batman: Arkham Asylum; my 2009 GOTY, so that says enough.
- Street Fighter 4; the DualShock sticks aren't exactly arcade sticks, but they come close enough (for me) to make it an enjoyable game on the PS3
- BioShock 2; loved it.
- Fallout: New Vegas; has it's fair share of bugs and glitches on the PS3, but that's the case for every platform.
- AC:B but I don't need to mention that for this topic.
- Battlefield: Bad Company 2; loving it to death, I'm not noticing a lot of sniper whoring despite reports, maybe that's just for the PS3 or maybe I just get lucky.
- Red Dead Redemption; great game, loved it, haven't tried it online a lot, first time I did I couldn't find anyone to play with, might be a PS3 disadvantage.
- CoD: Modern Warfare 2; loved the singleplayer, became increasingly frustrated with the multi so I don't play it any more.
- Need for Speed: Shift; love the feel of it, best racer I played in ages.
- Castle Crashers; most fun download-only title I've ever played, hard to find people online for it though, might be easier on the 360.
- Shank; fun little snack for between 'big games'.
- WipeOut HD; very fun arcade racer, I can recommend it.
- Resistance 2; very fun shooter, had lots of fun with the campaign but I didn't check out the multiplayer a lot.
And that's it for me. From what I've heard the Ratchet & Clank series is also to be recommended, have yet to check it out but I will soon enough. My little brother also has the God of War HD Collection which is a ton of fun, so I bet God of War 3 is awesome as well. Loved the demo for that anyway.