Sorry you guys did not all know about this resource, explicitly (there have been links to recordings in Muscat threads now and then)! -- The digitization of cylinders and 78s, etc was begun 15 or so years ago when I was a PhD student there at UC Santa Barbara. I was called in to identify some Indian (South Asian) records.

More recently, I have found the accordion recordings to be insightful. To hear the things people could do on the old instruments is humbling.

The other great (related) resource at UC Santa Barbara is the English broadside ballad archive. One of its distinguishing features is that the researchers sought (and continue to seek) tunes for the ballads, and they get people to record the ballads sung to the tunes, by way of example. I'm usually hesitant to mention this archive because I sang a number of the ballads for the recordings but, alas, was not in a position to work on the renditions at the time (there was a bit of a press at the time to simply go through quickly and get many recorded) and consequently I'm quite embarrassed about the finished products!
http://ebba.english.ucsb.edu