This reminds me of Cliff Stoll (<i>The Cuckoo's Egg</i>) giving a talk at the Dayton Ham radio Convention a few years ago about curiosity and how it seems to be dying these days.  He went out to the flea market and bought bags of parts and dumped them on the overhead projector and said, with some drama, "you can build a radio out of these".<p>He gave an illustration of an application of such technology for his neighborhood.  The street near a school had a speed limit that was often exceeded.  He wanted to find a way to bring the attention of this to the city.  Purchasing some parts from Ramsey Electronics, he built a radar gun (using licensed ham radio frequencies), attached it to a post near the street, connected the output to a macintosh, and delivered plots of the speed of cars over a period of time.  The city then put speed bumps there, making it a safer street.