Great historical resource from the Library of Congress. This description is from Marylaine Block's Neat New Stuff:
"National Jukebox - Historical Recordings of the Library of Congress
Right now it includes 10,000+ recordings made by the Victor Talking Machine Company between 1901 and 1925, with the promise to add more from Victor as well as from Sony and its associated labels. Searchable. You can also browse alphabetically by genre, by playlists (early Tin Pan Alley, the Fox Trot, Sousa's band, etc.), or by composers, performers and lyricists"