I have a ton of PSN games, minus a few that didn't interest me (like Brain Age etc). So feel free to message me with which ones interest you and I can give my honest opinion of them.
But a few I would recommend, but really depends on what type of thing you are in to:
SuperStarDust HD (great shooter, multiplayer)
The Last Guy (fun game, but gets VERY hard on later levels)
Flower (amazing visuals, and does a good job stirring emotions)
Calling All Cars (A fun little game, good to play with friends)
Pixeljunk Monsters & Eden (Pixeljunk series have a good reputation and are very fun)
Crash Commando (2D shooter, fun game to mess around with)
WipeOut HD (Lots of content, and comes with possible Platinum trophy, however it is very hard to get it)
Savage Moon (If you love tower defense games, this is a good choice)
Comet Crash (Again, tower defense game, but this time you attack back! I enjoy this game a lot)
Rag Doll Kung-Fu (A fun game to play with friends, not so much solo)
Bomberman ULTRA (It's Bomberman!!!)
High Velocity Bowling (If you like these types of games, it can be a lot of fun, multiplayer/online also)
Wolfenstein 3d (Old skool fix!)
Zen Pinball (I've always loved pinball games, so I am slightly biased, but it comes with 4 tables and is a decent game)
Age of Booty (Found it to be a lot of fun, a little pirate ship strategy game)
Games I've bought and regretted:
Blast Factor
Super Puzzle Fighter II Turbo HD Remix
Puzzle Quest
Noby Noby Boy (weeeeeeird game, but I bought it to support the creator, he's an awesome guy)