I love it when an application is unobtrusive and functional. You don't get many of these from Apple's App Store because they have such strict rules for developers. There must be an icon added to the home screen and there are certain parts of iOS the app cannot access.
This is a big reason why my iDevices are jailbroken and why I like Cydia so much. It's basically a hot bed for innovation as developers have far less limitations when submitting apps to the Cydia Store. FlipOver is a perfect example of that innovation...