Sheet Music Archive, The:Large selection of public domain classical sheet music, including the great works of famous composers.
247 Sheet Music: Free sheet music downloads for piano in PDF format by Bach, Beethoven, Chopin, Debussy and Joplin.
Anne's Free Sheet Music: This site has a few public domain scores available. Corelli, Bach, Pachelbel and others are represented.
Breizh Partitions: Hundreds of free Celtic scores for bagpipe, fiddle, piano, guitar, flute, or other instruments.
Cipoo: Free choral public domain sheet music, MIDIs and MP3s.
Free Sheet Music Source: Free public domain sheet music, including choral, spiritual, piano, organ, and brass sheet music.
Musopen.com: Free Public Domain Music - Musopen.com Musopen is a community driven, online music repository.
Mutopia: Open-source sheet music in PDF, PS, and GNU LilyPond formats. Mostly classical, with a little jazz.
Petrucci Project, The: A project to digitize public domain sheet music. Some scores are available.
Ragtime Sheet Music and Books: A source for ragtime music. Includes some downloadable tunes in GIF format and a links to other ragtime music.
RowyNet: Free sheet music, online multilingual music glossary and selected links to classical music scores.
The Choral Public Domain Library: An extensive archive of choral music in the public domain.
Tom's Public Domain Sheet Music Library: Public domain (in the USA) sheet music of folk songs, hymns, spirituals, etc. with melody, lyrics, choral and/or piano. Available as lilypond inputs, and usually as PDF and/or Postscript.
Werner Icking Music Archive: A continuation of the now defunct GMD Music Archive. Browse a large collection of Public Domain music.