Here's a cute universal app with limited utility but great creativity. Chameleon Clock, selling for US $0.99, captures the background behind your iPad or iPhone using the built-in camera, then superimposes the time and date above that scene. The result is an illusion of a transparent iPad or iPhone. It can be very startling if seen from the right angle, where background and live clip line up perfectly. Even if you are moving around, it's still a nifty background for the clock.
If you tap the clock, letters and numbers toggle between white and black. Sliding your fingers up or down and the on-screen time and date fades to nothing.
There are two modes with the camera. One picks up live video, the other looks at the color hues behind your device and renders a mix of colors. As the lighting in your room changes, the color wash changes.
The app works in horizontal or vertical mode. This is a pretty basic clock. No alarms or reminders. I would have liked to see control over fonts, sizes and placement, but hey, it's main claim to fame is the ability to act like a chameleon.