MEOWSER is a (M)ineral (E)lement Br(owser): a wooden display cabinet containing rocks and mineral samples with LED lighting controlled from a laptop computer.  The laptop can display either the periodic table or a layout of the cabinets.  When the user mouses over elements or minerals the appropriate lights in the wooden cabinet light up.  An Arduino microcontroller serves as the computer – LED interface.

Here’s the video explaining how it works: