Historic American Sheet Music - The Rare Book, Manuscript, and Special Collections Library at Duke University: Major collection of sheet music; digital images of 3042 pieces published in the US, 1850-1920.
Amoskeag Music - Historical musician Bob Kilham recreates the sights and sounds of antebellum America using original or reproduction instruments and primary source music.
Cowboy Songs - A reference library of classic western and cowboy songs.
Dr. Horsehair - Recordings and banjo instruction books in the modern-day clawhammer banjo or frailing style and the old-time minstrel banjo stroke style.
Halcyon Days Music - Midi music collection of early American music of the 19th Century and early 20th Century, complete with scans of sheet music covers and lyrics.