Print Free Staff Paper
- Printing free blank staff paper in a variety of formats including ensembles, solo instruments and choral.
- http://www.pdfpad.com/staffpaper/

BlankSheetMusic.net
- Blank sheet music to print for free, supports multiple keys and formats, guitar and bass tabs too.
- http://www.blanksheetmusic.net

Abacci Music
- Irish, celtic and world sheet music, midi files and tab.
- http://www.abacci.com/music/default.asp

NotaViva
- Free pieces in PDF format by various Classical composers as well as educational music.
- http://www.notaviva.com

8notes.com
- Collection and directory of free sheet music pieces and lessons for piano, guitar, violin and other instruments.
- http://www.8notes.com/

Music Sheaf
- Features manuscript staff paper in several customizable formats.
- http://www.musicsheaf.com

Sibelius Music
- Showcase site for the Sibelius plugin 'Scorch' - includes several thousand pay-per-download files and some free users files.
- http://www.sibeliusmusic.com

Anyscore
- Mainly commercial sheet music with some free downloads. Includes self-published scores by living composers.
- http://www.anyscore.com