astroglasses -- LED chaser
Constructed for an optometrist's office, this mesmerizing piece cycles through a nearly infinite variety of patterns and speeds.
Small infrared (IR) emitters and a single IR detector signal to the microcontroller "brain" when someone is in front of the piece, and whether they are "left", "center" or "right". It then reacts accordingly.
The same detector is used for sensing when any television/DVD remote control is aimed at the front of the piece -- this feature allows for user selection of the current "pattern".