You know i searched long and hard for something like that about a year ago, but after about 6 hours straight of digging on the net, I had come up with nothing. I suppose the main reason for a lack of software like this is the fact that most, if not all, of the current PPC's lack any sort of MIDI hardware. I guess it would be possible to write a software only sythesizer but I'm sure sound quality would be lacking and it might suck up too much processor speed.
My solution:
I sat down with my mic and guitar and spent an hour recording each note and each basic chord and saved them all as separate .wav files. It was a pain but really the only way I could find to make the program I was trying to make. Of course, this was a year ago and i haven't done any hardcore searching since then, so maybe something popped up, but i doubt it.
