Here are some lovely 3D ones (all demos/light). Good for wasting time while waiting at places
labyrinth lite - accelerometer based game (get the ball from A to B)
Blockx 3D - 3D tetris
Light racer 3D - tron style racing with light bikes
Speed Forge 3D - easily the best 3D game so far (graphically), gameplay is also nice
If you want an addicting game, check out
Farm Frenzy, it's not 3D but it should be illegal to make such addicting games
