I've been trying to pimp out my PSP collection recently as well.
Like Travis already pointed out, Final Fantasy VII - Crisis Core is meant to be good. My copy arrived a couple days ago and I've played it for about two hours so far. I'm not really far enough in to give a full opinion, but it's not your typical turn based combat. It does kinda just feel like I'm mashing the X button in battles a lot, but I suppose it wont be so easy later in the game... I hope.
Also picked up a JRPG called Popolocrios. Still not gotten around to playing this yet, but it's meant to be quite good. It has quite a nice art style and anime cut scenes, so it's pretty enough to look at. From what I've heard it's also a pretty good game.
There's a few other games I've been looking at, but they're quite expensive in the UK. Breath of Fire III, Star Ocean: First Departure and Star Ocean: Second Evolution. Again, all JRPGs and those all happen to be ports of older games. I've been told that First Departure might be hard to get into because it does feel old, but they look like interesting games.
I'll try to keep you updated if I get any cool PSP titles in the near future.