National Jukebox Historical sound recordings from the Library of Congress.
LiederNet Archive Word-for-word translations and texts for vocal pieces.
The Piano Education Page For pianists, teachers, and students. Articles, composer bios, over 600 MIDI files and practical information; also useful to music educators in general.
American Memories site from the Library of Congress and Performing Arts Encyclopedia from the Library of Congress Digitized collections relating to American music.
Free Music Scores International sheet music for 35 different instruments
Musical Scores (Eastman School of Music, Sibley Library)
19th Century American Sheet Music University of North Carolina at Chapel Hill
WLSCM Web Library of Seventeenth-Century Music
New York Philharmonic Leon Levy Digital Archives
DIAMM Digital Image Archive of Medieval Music
African American Sheet Music at Brown University
Indiana University Variations Online Musical Scores
Gallica Bibliotheque Nationale de France
British Library Online Gallery
University of North Texas Virtual Music Rare Book Room focus on 18th Century Opera
Music Treasures Consortium Library of Congress