Music Minus One 
Recordings of Classical music minus solo instrument for students to accompany.
http://www.musicminusone.com/MusicNow
Contemporary classical music by British composers and performers as well as world and community music.
http://www.musicnow.co.uk/
Musical Observations Inc
Recordings by Paul Zukofsky and others of Schnabel, Cage, Feldman, Scelsi, Leifs and others.
http://www.musicalobservations.com
Merlin Classics
Independent label for Classical music from light Classical to Contemporary works.
http://www.merlinclassics.com/
Marston Records
Label in Swarthmore, Pennsylvania offers program notes on singers and recordings, many of historical significance.
http://www.marstonrecords.com/html/catalogue.htm
