Hey,
I found this site that is a great source of samples. The University of California at Santa Barbara has digitized 6,000 cylinders with music from the late 1800s and early 1900s. They're free for download at http://cylinders.library.ucsb.edu/.
Dang, that is awesome. But I couldn't figure out how to download the actual library cylinders...all I could hear was the 'featured' cylinder in the upper right. What am I missing?
Yeah, it doesn't seem to be working right now. It was featured in the New York Times today so they're probably getting more traffic than they can accomodate. Should work in a day or two, once the novelty wears off.