In the Gummi, the team has combined a standard, rigid LCD with sensors and a touch pad all mounted in a flexible acrylic plastic block. Users can manipulate information on the screen by flexing the board and using the touch-sensitive pad to control the content. Piezoelectric pressure sensors, which generate a voltage when deformed, are built into the Gummi to detect the flexing...The resulting device would have no conventional mechanical parts. You would steer the cursor using a touch panel on the reverse of the mini PC, while pushing the middle of the device in or out would let you browse through a menu. Bending could also control tasks such as zooming in and out of a map, controlling the playback speed of video files and editing the composition of image layers.
Finally... something kinda out there and interesting. I don't know if it will ever work, but Sony's Interaction Lab has come up with a pretty cool concept for eliminating buttons and avoiding the easy blunders of an exposed touch screen.