Planet Puzzle League, fun as hell, full stylus (optional) game
Kirby Mass Attack, Kirby Canvas Curse
Bejeweled Twist
Electroplankton
Puyopop Fever
Wario: Master of Disguise
Picross DS, Picross 3D
Geometry Wars Retro Evolved (if you don't mind playing in lefthanded mode)
Might and Magic Clash of...