Something For Nothing?

Is it possible to operate an electronics circuit without benefit of external power?  How about receiving radio waves without battery or commercial power of any sort?  I'm not talking green here.  Not aluding to solar or wind or even lemon power.  No power at all from any outside source, other than the radio signal itself.

The very first radio receivers did just that.  Not only did the very first radio receivers operate power free, but also, very often, the very first radio receiver a modern day electronics experiementer builds and operates, operates in this fashion.  Like the very first small bicycle a small child rides - training wheels and all - until he or she can grow up just a bit and graduate to a "real" bike, a simple crystal radio receiver sparks that inititial interest.

This page is going to have some interesting info on crystal radios.
I just have to finish it - pictures, story, and all.
Please be patient.........