Well "app" is a bit misleading, it's actually a game. Something fun to play while you're sitting in heavy traffic or at a long stop light. Passengers should enjoy it too.
I know we'll be getting off-topic for this thread, so maybe another can be started. What kind of game if you don't mind spilling the beans?
I was thinking of a couple that would work quite well today: A sideways break-out/arkanoid type game. Allowing to play from the right or left. Maybe letting certain levels flip the sides on you just for the hell of it (difficulty :)
Of course the screen is big enough and the processor powerful enough to do a lot more complex gaming. The controls are about the most challenging for the player. How about a small Karateka? Or Bruce Lee style game? (Think back, waaaay back - from Data East for the Commodore 64 and others)
Of course a cool visualization of stick-men kicking the crap out of each other super-king-fu style would be really nice too (anyone who's seen the flash animations of same will know exactly what I mean :)
Bruno