I had loads of fun with Dirt 2, single player and multiplayer.
I really enjoyed Mass Effect.
Batman Arkham Asylum was great. Great graphics, great story, great gameplay.
Dead Space, excellent, very atmospheric, good story and premise. Haunted house in space kinda deal.
Another game that is just pure fun and I found myself playing for hours on end was Just Cause 2. Huge open world, loads of weapons and vehicles, smooth graphics engine, could be a bit repetitive but all in all tons of fun.
I thought Tomb Raider (the recent reboot) was fantastic, the shoot and cover mechanic out did Uncharted imho.
The last PS3 game I played and finished was Alien Isolation. The best Aliens franchise game ever imo. Captured the atmosphere of the Alien universe perfectly, although the graphics engine on the PS3 was quite rough around the edges. A great experience, very tense and scary. The game annoyed me at first as I tried to get used to it, but once I got to grips with it and got into the flow of the thing it became a very good game indeed. Outwitting the Xenomorph was very satisfying, as was using it as a weapon/decoy against human enemies. Yeah great game that.
The Last of Us was very good, yes I shed one or two tears, you know what I'm talking about, I just couldn't help it.
Killzone 2 was a great war simulator. It captured the chaos and insanity of armed conflict quite well I reckon, makes you wonder why the hell anyone would join the armed forces and go to war, as it is hell on earth, or in this case Helgan.
Uncharted was great, the first PS3 game I bought and finished.
I've probably forgot a few. But yeah, a good system, shame it was underused in many cases, I'm talking about the poor X360 ports, but that was as much Sony's fault as the lazy developers. Oh and the less said about Bethesda's treatment of PS3 owners the better, a diabolical company.