Links:

Colin MacDonald's Ragtime March Waltz Web Site - More than 300 ragtime sequences.
Early American Music - Halcyon Days Music - Collection of Early American music from the 19th to early 20th Century in MIDI music format. Ragtime, Fox Trots, Dancing songs included with scans of sheet music and lyrics.
John Farrell's MIDI File Page - Jazz piano MIDI files, mostly John Farrell's transcriptions of recordings by famous traditional jazz and stride pianists.
John Roache's Ragtime MIDI Library - Complete collection of John Roache's Ragtime, Swing, Jazz and Stride Piano MIDI performances; links; MIDI and Ragtime FAQs; Profiles of ragtime performers and composers. Includes music by Robin Frost, Frank French, James P. Johnson, Scott Joplin, James Scott, Eubie Blake, etc.
Keeper's long-lost MIDI files - Sequences from 1988 to the present of mostly ragtime and baroque keyboard works. Includes original ragtime compositions by the founder of the rec.music.ragtime newsgroup.