Want to add some switches and dials to your wall without running all those wires? Or perhaps it would be nice to animate that drawing of a control panel that you made? Well then, you might want to take a look at the PUCK, the latest project by Eric Gradman and Brent Bushnell. Their solution uses a single control that the user can move from place to place, that takes on different actions depending on where it is located. To sense location, they embed RFID tags into their drawing. Then, when the controller is placed over a tag, it reads the ID and then starts sending control messages to whatever knob it is underneath. Powering this all are the standard Arduino and xBee modules, plugged into a custom PCB. Ok, I want to see some interactive puzzles based on this!