Berklee Press - Books and recordings covering all instruments and all main music topics.
Cassette and Video Learning Systems - Instructional books, DVDs and video for guitar, bass, keyboards, drums, harmonica, banjo mandolin, violin and fiddle.
Music Minus One - Participatory recordings and accompaniment music for musicians and vocalists, including all styles.
Musician's Workshop - Video and audio products for string and keyboard instruments, harmonica, and tinwhistle.
MusickEd.com - Study guides and learning tools for all instruments. Also online lessons.
Musicridge - Offers instructional videos for accordion, stringed instruments, drums, and brass ensembles.
Musicroom.com - Music tuition and music-related books for all instruments.
MVP: Music - Offers an extensive collection of instructional videos.
One Day at a Time - Offers a selection of musical instructional products for all instruments and styles.
Perfect Pitch - Offers a training program by David Lucas Burge, designed to teach pitch recognition by ear. Includes research information, and a partial lesson.
Pro Audio Music - Wide selection of books, videos, CDs and software for all instruments and music topics.
Ron Greene's Music Dials - Visual reference guides that show the chords and scales you can play with all instruments.