In my survivalist searchings, I was looking for a way to make a transistor radio from household items should we suffer a NBC attack.
Kidding.
But it does serve that purpose if needed. I found some pretty cool radios, and a laser pointer, point to point communication system. Even a way to create a chat system, with your computer, without the internet. Good stuff to do with your kids.
Scitoys.com
Good for camp counselors, scoutmasters, outdoors....
lots of uses.
I'm going to try the three penny radio this weekend maybe...