Jeanne D'Arc was incredible on the PSP. I also really enjoyed Dungeon Siege: Throne of Agony, which did a good job at translating the fully fledged PC game into a mobile experience. Stranger still, the fact that Dungeon Siege was somewhat a Microsoft Games IP as well...
So many good games on this console, and it was an absolute powerhouse. I've still got one that works, and a decent collection of games for it.
Yeah, there are a lot of amazing things on this platform. Gotta find a reasonably priced battery soon to delve deeper!
Also, there is that leaked development build of Elder Scrolls Travels: Oblivion which is really intriguing.