I created an iOS app http://ideon.co/theconverted/ as a side project. I've had hopes to be able to survive entirely on revenue from my own projects instead of relying on client work. I'm very far from that goal at this point, but the extra income is nice.
Thanks! GUI and animations are all custom. I wanted very specific multitouch capabilities that would not be practical by using standard gesture recognizers. So a lot of work went into imitating the rubber banding and momentum scrolling of the all-familiar scroll view. It was definitely worth it in my view. Said gestures manipulate two base values; origin, and scale (1D scroll and zoom.) Values on each side are defined as a multiple and an offset of the base (linear function.) All numbers on screen are basically entities of a particle system and are spawned, positioned, and destroyed according to their relation to origin and scale.
