I'm always looking for great examples of hardware and software coming together.  SenseSurface got me very excited.  It is real physical turn dials being applied to laptop screens to control software. The knobs are magnetic and promise to be gentle on your screens.  The sensing knobs have a custom designed  movement sensor to determine position within approx 180 degrees with a 10 bit digital output, linearity typically 1%.  Designed by Lyndsay Williams.