Do you have an iPod Touch or an iPhone? If you do, you should go to the apps store and get toppler. Right now it's free, and it really shows how nice the tilt sensor is on the system. If that impresses you, you should definitely get Dropship. At the moment, it's temporarily 99 cents, and it's a remarkable twin-stick shooter with performance I wouldn't have thought possible for such a little system.
The same company has also released a game called Rolando, but I haven't summoned the courage to drop the ten dollars. It's been described as the Mario Bros. of the system, and I've only heard good things.
If you have an iPhone, you clearly have some money to spare; at least give Dropship a chance if you like space shooters. I think you'll be impressed.