I have been thinking of something like this for years, but the goodly geeks at MIT Nerd Kits have created it - and let's face it, they have the skills I lack in the area of electrical engineering. Circuit Lab is a virtual schematic designer and tester with many great tools. Funnily enough, the day my DSONano oscilloscope arrived via FedEx, I find out about Circuit Lab from Nerd Kits. Now you can see what putting 100v into a 555 chip does without blowing it to smithereens!
Check them both out if you want to learn how to make tiny circuit bits do their thing in useful ways.
I'm already in love with the DSONano just because it looks like a cool bit of Star Trek kit right in your hands. It is packed with functions and I can't wait to actually be able to put it to practical use!