Loco Roco, Patapon, (Patapon2 and LocoRoco2 But they're not out yet, but they look great), Crisis Core, Tales of Eternia, Tales of Legendia 2, Tales of the World: Radiant Mythology, Disgaea PSP (has exclusive features, and I don't consider the DS game at all, so your request of exclusivity is fulfilled), WipEout Pulse, Grand Theft Auto Liberty/Vice City Stories (2 games there
), Gitaroo Man Lives!, Me and My Katamari, and Sonic Rivals 1+2 which are far better than the crappy Rush games on DS (at least, in my opinion). SOCOM FTB 2, PaRappa the Rapper (debatable), flOw (PSN title. not really a game exactly but fun!), all the PSP Megaman games _>
Echochrome as well is pretty good btw