Since you asked...

A Summer Challenge >>> Some of you were interested in actually sending your own radio signals - I have no idea how -- but here are some sites that give instructions, and of course you can google your own:

http://sci-toys.com/scitoys/scitoys/radio/am_transmitter.html

http://www.instructables.com/id/Make-Your-Own-Low-Power-AM-Radio-Transmitter/?ALLSTEPS

Either of these directions involves buying several parts, an oscillator and a transistor and a board.  Let me know if you get it going.  And have a wonderful summer.

OR: how about a solar powered electromagnetic pendulum - the best of all possible combos!  http://makezine.com/2010/06/02/beautiful-solar-pendulum-build/