From the Maker Faire blog: Unlimited Derby entry by Tim Brandt
“I have for the past several years made different cars for Pinewood Derby Races. Two are legal cars and two are unlimited cars. These cars all have one thing in common. They all have Micro Controllers and sensors to tell when they are moving and to cause something to happen. The two weight legal cars just had blinky lights and sound effects. The other two have motors. One has standard small RC rear end and the other uses an Electric Ducted Fan Unit. The one with the EDF also has blinky lights which were not working for the race shown on the youtube video from 3/6/10.
See it in action: http://www.youtube.com/watch?v=GqVc_Hr8UNo