Last Clock (iPad)
Great looking app by New Mediology that uses the live camera feed as a source from which to display the clock. The seconds, minutes and hours tick by as an abstract representation of the iPad's surroundings. A bit difficult to explain, best just to watch the video.
Dream Track Nation (iPhone, iPad)
Lovely little racing game with loads of personality and a charming style.
The Invisible Universe (Android)
The nice idea behind this app is that you can see all the gases and rays that surround you every day. Great use of GPS and device orientation to make the invisible visible.