Weird that we've been getting these PSP vs. DS threads lately. I have a PSP and love it. Here's a post I made of games I have enjoyed and have been reviewed well by the critics separated by rough genres:
Racing
Wipeout Pure and Pulse
Shooters
Killzone Liberation
Syphon Filter Dark Mirror and Logan's Shadow
Socom Fire Team Bravo
Sandbox
GTA Liberty City and Vice City
RPG
Brave Story
Disgaea
Final Fantasy Tactics
Jeanne D'Arc
FF Crisis Core
Valkyrie Profile
Platformers
Daxter
Ratchet and Clank
Castlevania Dracula X
Stealth Action
Metal Gear Portable Ops
Action
God of War
Pursuit Force 1 and 2
Action RPG
Monster Hunter
Gurumin
Adventure
Sid Meier's Pirates
Strategy
Field Commander
Puzzle
Puzzle Quest
Lumines
Crush
Echochrome
Music
Beats
Other
Patapon
Loco Roco
My Top 5:
Shadow of the Colossus, Metal Gear Solid 3, Shenmue, Skies of Arcadia, Chrono Trigger
My 2 nex-gen systems: PS3 
and Wii 
Prediction Aug '08: We see the PSP2 released fall '09. Graphically, it's basically the same as the current system. UMD drive ditched and replaced by 4-8gb on board flash memory. Other upgrades: 2nd analog nub, touchscreen, blutooth, motion sensor. Design: Flip-style or slider. Size: Think Iphone. Cost: $199. Will be profitable on day 1.
