Quest for Booty (QFB) is the Ratchet and Clank expansion on the PSN.

There is a demo of Warhawk on the PSN store, it has some tutorials and one map that is a CTF/zones game. I played the demo for about 25 hours it was that good, the dogfights were my favorite part.

I would also recommend PixelJunk Monsters (Single player/co-op). I can't say enough about that terrific game. Very cheap too!

Warhawk.  I know it's been mentioned plenty of times, but it is my favorite multiplayer game this gen next to TF2 (PC).  Even if I'm not that good at it lol.

I also rather enjoy MGO, but it seems to be a love it or hate it game.

Outside of shooters, LBP and Wipeout HD are fun.

uncharted, mgs 4 for single player. I'm gna go wif resistance 2 and littlebigplanet for online but i'm pretty sure u'll enjoy killzone 2 more cuzz if u like online u like call of duty im gna guess and dose games seem to be similar from da videos so jus wait for dat

Don't get Ninja Gaiden Sigma. It is awful. Really, really awful. It hates the player. With a vengeance.

From what I've played of Resistance (not a lot), it is nothing like Halo, and is quite unique.

LBP go ahead

MGS4 has an excellent single player campaign, with a great story. The online isn't as horrible as people seem to think, it's actually very good. The only annoying thing is that you have to sign up for a GAME ID and KONAMI ID on the website- it's not done through PSN, but through Konami's servers. MGO is very different. You have the classic cardboard box, great shooting, and several game modes, one (two) of which DOES (do) involve stealth.

Uncharted has great single player, but the multiplayer is awful, mostly because there isn't any :P

Warhawk is a love it/hate it thing. There's a demo on PSN, try it.

Warhawk for $20 is a steal.

R2 MP and Co-op was fun, I'll purchase the game when I have the chance (and before Killzone 2)

LBP is fun online

SOCOM had issues at launch but those supposedly were patched....I enjoyed the demo.

For SP

Uncharted without a doubt one of the best games this generation, I played through it like 4 times.

MGS4

Heavenly Sword if you can find it cheap

Ratchet FTOD

Ratchet Q4B

Hmmm I kind of wish IGN would do a re review. I generally enjoy their reviews over others.

I forgot Ratchet and Clank Future: Tools of Destruction.

That is an amazing game.

My other three favourites; BioShock, Oblivion and CoD4; are multiplat.

Get Warhawk. Walmart and probably some other stores sell the headset bundle for $20. The game is epic.

SOCOM has been patched up and works better than before. The game is very fun and encourages you to work as a team. There are a few problems with it, so I suggest you wait for the next update.