A non-self-righteous Apple feature post

This isn't new, but it's interesting and fun in terms of new uses for semi-new technology. All new powerbooks have a motion sensor to stop the hard drives to prevent damage in case you drop it. These sensors are quite sensitive, so much so that their output is precise enough to use physical movement of the computer to control programs and elements onscreen:
The Apple Motion Sensor As A Human Interface Device

Just check out the video of playing netball by tilting the computer to see a simple implementation of this software.

Another person has already developed a similar game based on the software, Bubblegym.