Homespun Tapes 
Wide selection of videos, CDs and audio cassettes for all instruments and styles.
https://www.homespuntapes.com/Mike Mangini's Rhythm Knowledge Online 
It offers rhythm instruction materials for all instruments.
http://www.rhythmknowledge.com/
Dr Downing Music 
Troubleshooting books for all musicians.
http://www.drdowningmusic.com
ADG Productions 
Books, CDs, videos and software for most instruments and styles.
http://www.adgproductions.com/
Southern Music Company 
Sheet music and methods for all instruments and ensembles.
http://www.southernmusic.com/
Musician's Workshop 
Video and audio products for string and keyboard instruments, harmonica, and tinwhistle.
http://www.musicians-workshop.com/
Berklee Press 
Books and recordings covering all instruments and all main music topics.
http://www.berkleepress.com/
Edly's Musical EdVentures 
Sells two books: one for to learn music theory and one for piano.
http://www.edly.com/
Music Minus One 
Participatory recordings and accompaniment music for musicians and vocalists, including all styles.
http://www.musicminusone.com/
MusickEd.com 
Study guides and learning tools for all instruments. Also online lessons.
http://musicked.com/
Cassette and Video Learning Systems 
Instructional books, DVDs and video for guitar, bass, keyboards, drums, harmonica, banjo mandolin, violin and fiddle.
http://www.cvls.com/
Music in Motion 
Sells books, videos, audios, awards, teaching aids, posters, gifts and software.
http://www.musicmotion.com/
Comprehensive Ear Training 
A progressively graded series of books, CDs, cassettes, and MIDI discs.
http://www.keystrokepublishing.com/
Healing Music 
Books, CDs and tapes for to practice singing and songwriting.
http://www.healingmusic.net/
Allstate Sight Reading 
Books for all instruments and choral students.
http://home.att.net/~l.mclure/
Flying Leap Music 
Publishers of You've Got Rhythm, a method to learn and improve music-reading skills.
http://www.fleap.com/
Creative Horizons Music 
Sells biblical psalms sheet music, a chord scale chart, and a handbook explaining music theory.
http://www.creativehorizonsmusic.com/
Comp-U-Xpress, Inc. 
Offers songbooks and instructional books, CDs, and DVDs for various instruments and styles.
http://www.easymusicbooks.com/
Allegro Music Online 
Complete line of products including popular piano methods and Suzuki materials.
http://www.allegromusiconline.com/
Pro Audio Music 
Wide selection of books, videos, CDs and software for all instruments and music topics.
http://proaudiomusic.com/educational.htm
MVP: Music 
Offers an extensive collection of instructional videos.
http://www.mvphomevideo.com/
One Day at a Time 
Offers a selection of musical instructional products for all instruments and styles.
http://www.1dayx.com/
Music Message International 
Offering instructional videos for several instruments.
http://www.musicmessage.com/
ModRock.com 
Guitar tabs, books, videos, sheet music, and CDs for all instruments.
http://www.modrock.com/
Musicridge 
Offers instructional videos for accordion, stringed instruments, drums, and brass ensembles.
http://www.musicridge.com/
Ron Greene's Music Dials 
Visual reference guides that show the chords and scales you can play with all instruments.
http://www.musicdials.com/
Musicroom.com 
Music tuition and music-related books for all instruments.
http://www.musicroom.com/mfschools.ihtml
Letsplaymusic.com 
Offering several educational books for accordion, harmonica, and guitar.
http://www.letsplaymusic.com/
Perfect Pitch 
Offers a training program by David Lucas Burge, designed to teach pitch recognition by ear. Includes research information, and a partial lesson.
http://www.perfectpitch.com