For DS (I have a PSP as well but their game selection just isn't as good.)
Disgaea
Castlevania Order of Ecclesia (prob the best one after SOTN)
Rune Factory 2
The World Ends With You (Best rpg on DS IMO)
Valkyrie Profile Covenant of the Plume
Summon Night Twin Age
Megaman StarForce 1 and 2
Suikoden Tierkreis
Magical Starsign
Avalon Code
Final Fantasy Tactics A2
Final Fantasy Crystal Chronicles: Ring of Fates
Final Fantasy Crystal Chronicles: Echoes of Time
Phantasy Star Zero and Shin Megami Tensei: Devil Survivor look to be good pick ups too once they come out
