Heavenly Sword is really good God of War-ripoff. Too bad it's very short. Also has one of the best main villains in any game.
Darksiders plays awesomely on PS3, though you might want to get PC-version if your system can handle it. It's Legend of Zelda + God of War + a little bit of Portal at the end.
Dante's Inferno is (also) pretty good rip-off os God of War (yes, I like GoW ripoffs) that's pretty twisted in a good way. Some people are bashing it because it's "not exactly as Divine Comedy, boohoo."
WET is something in line of "if Suda51 made Max Payne." It's pretty fun.
Way of the Samurai 3 is plain awesome. If you like feudal Japan-things, this is a must-buy. Includes loads of swords and you can pick any NPC-model after you beat them up in game.
Yakuza 3 is Yakuza. Modern beat em' up that has deep storyline and lots of content. Yakuza-series are basically successor of Shenmue.
NIER is supposed to be actually a good game, can't vouch for it tho'.
As for PSN games,
Castle Crashers is awesome. Buy it. Buy it now.
Shank also plays much better with controller but if you own pad for PC you might want PC-version. And then there is
Ratchet & Clank: Quest For Booty, a cheap R&C shortie for PSN. It's also avaible on disc in Europe.
You might also find something interestin in here:
http://vsrecommendedgames.wikia.com/wiki/Playstation_3