I had plans, many years ago, to do something like this, but with a bit of a twist. A complete digital electronics training / development system, half virtual (like what you have done here) -- and half "real". The real part would have plugged into your parallel port (of course today though you'd go with USB) -- and allowed the user to setup the circuits on it, just as they see it on their screen. The virtual side would check the circuit and spit out exercises to complete.

I actually presented the idea to Silicon Chip. They thought it sucked harder than a heated vacuum cleaner..

Trent Jackson