PSN titles:
Flower - Beautiful game that everyone should try out
Pixeljunk anything except racer - they're always fun
Shatter - best brick breaker game in a long time
Braid - a fantastic puzzle game with a cool story near the end
Wipeout HD - crazy graphics and fun fast racing gameplay.
PS3 titles:
skate 2 - if you were ever a skater
Batman: AA - if you were ever a Batman fan
those are the only "non obvious" ones I can think of.
...