A Jazz Improvisation Primer, by Marc Sabatella
Detailed online course in jazz improvisation with pages in history, theory, and practical advice on playing in a group.
Brent D. Stuntzner's Jazz Guitar Site
A jazz guitar site featuring transcriptions of solos. Formats include standard notation, TAB, MIDI, and Jam Tracks.
Guitar Lesson World by Patrick McFarlane
Progressive series of 50 guitar lessons for the improvising musician, including soloing and comping.
Jazclass with Michael Furstner
A basic primer on jazz improvisation using chord root tones and chord guide tones.
Jazz Arranging Tutorial
Web-based instruction in jazz ensemble writing. Based on charts for the University of Northern Colorado Jazz Lab Band. Offered by Alabama State music professor Doug Bristol.
Sax on the Web: Tim Price
Selmer clinician from the New York area offers online instruction harmonic substitution, with exercises to improve phrasing and improvisation and a series of "Bird-ology" studies.
Swing and Jump Blues Guitar
Matthieu Brandt, a guitarist from Amsterdam, Netherlands, offers detailed progressive lessons. Topics include chords, riffs, comping, turnarounds, and timing.