Jim and Marianne’s Jukebox is a pretty good sized collection of mp3-format recordings of old 78’s, including the catchy Great War ditties, Down in the U-17, I’ve Got My Captain Working for me Now, and Wilhelm the Grocer. I formerly had this collection stored locally, but it was lost in the great hard-drive corruption disaster of two-thousand-ought-three ([homer] stupid upgrades [/homer]). I would play them whilst engaged in aerial combat in the rickety WW1 combat flight sim Dawn of Aces.
Some time ago, I recall seeing a pointer on MeFi, probably from the remarkable music historian y2karl, to another hobbyist’s archive of material, but alas, I cain’t find it.
While looking for it I did find David Lynch’s “Old-Time Music Home Page,” coming to you straight outta Asheville, NC. I would commend your attn. to the links section, which included a pointer to Norm’s 78 Record Room, now apparently defunct – or maybe just spotty – it looks like a transient URL. I believe Norm’s was one of the archives I was looking for.
honkingduck.com offers 701 78’s in RA format (pfoo, but I understand).
Ah well – while I have a personal fondness for the mp3 transfers created and curated by hobbyists, academic folkorists have done a bang up job on the material, such as the music collections seen at the Appalachian Music Archives, the Smithsonian’s American Memory (which I’m sure you are all familiar with by now).