Very cool project. I particularly like fretboard.py, I'm a sucker for charming command line tools like this. For what it's worth, I have a bachelor's in classical guitar and I taught guitar for 6 years. It would be cool if you could get a single form of a scale instead of an entire fretboard of scale notes, and maybe even limit it to some number of octaves. It would be useful to generate scale charts for students one piece at a time.