http://www.99centguitarlessons.com/JazzComping.html Best $15 ever spent on lessons of any kind. Rich, the instructor-head guru at GuitarCollege.com explains changes, substitutions, inversions, chromatics...in a way that simple guys like me can even understand. Think I paid $2 each for 7 lessons that include a very thoughtful video download that played perfectly with multiple passes through changes with explanations and slow tempo versions. Also includes tab of each lesson. Fantastic stuff. I'm going back for second helpings!