There are also midi audio files available. Chris Ricker's Fiddle Page Professional musician Chris Ricker put together this great site for violinists and fiddlers. There are over 750 traditional and folk tunes available here in JPG, GIF and ABC formats. There are also some MP3 audio files to download and enjoy. Here is free classical sheet music by various composers for several instruments.
Some pieces also come with midi files.
The printable sheet music is in PDF format and there are midi files as well. Here is a selection of classical piano pieces printable in PDF and GIF formats. The music is from collections copyrighted in the late 1800s. This site contains 15 pages of music in GIF format, some with melody only and some with chords included. There are also some midi files available.