​Musical U:  This website is headed by a great music educator named Christopher Sutton.  It's an outstanding resource for all things related to Music Theory, including ear training, scales, chord building, the Circle of Fifths, and more!  It's subscription based, but there's tons of free resources!

Recommended Resonator Resources

​​Suggestions?:  If you know of a great resource that Fretboard Toolbox users might find helpful, please let me know on my "Contact" link, which you can reach by clicking "Suggestions".   

​​​Reso Hangout:  Reso Hangout is the go-to place for all things Resonator Guitar!