MIDI guitars are too expensive though. However, you can get cheap electrical guitars for less than the price of some guitar hero controllers. I wish I had more time to try out implementing this.

A question for you physicists & musicians :
What is the waveform of a guitar chord like ? For a single note I could use FFT to find the nearest sine frequency but what if multiple strings are plucked ? Is it additive and you would have to find the six dominant frequencies ?