If you're looking for product suggestions, Snap Circuits for the budding hacker child are great.
http://www.amazon.com/Elenco-SC-750-Snap-Circuits-Extreme/dp...
http://www.amazon.com/Elenco-SC-750-Snap-Circuits-Extreme/dp...
http://en.wikipedia.org/wiki/Gakken_EX-System
Denshi blocks are a fabulous way to learn electronics and they belong in your catalog.