Any PSP Game Recommendations?

I recieved a PSP from a friend of mine over Christmas, although gratefull for the gift, I was worried non the less of how much use I would get out of it. After picking up Persona 3 Portable, and Valkyria Chronicles 2 I've become extremely satisfied with it. Wondering what games you guys would recommend playing on it? Anything similair to P3 would be awesome. Much thanks to anyone who bothers responding to a question about PSP games!

any metal gear solid  game and syphon filter game. gotta love loco roco!