Here are the few PSN games I have already:
The Walking Dead, Flower, Fat Princess, Worms, PixelJunk Monster and Shooter, Dead Nation, Wipeout HD, The Tales of Monkey Island, Tumble, Hot Shots Golf, Risk: Factions, and some others.
What I've had in mind and never played:
Journey, Final Fantasy Tactics, The Cave, or Bully (one of my favorite PS2 games).
Any other suggestions? I'd be interested in RPG recommendations or unique games.