I recently discovered this Little Wonder Records Archive , an archive of 5 ½ ” about 90 second long records created between 1914 and 1923 to showcase the popular music of the time in a format that more people could afford.
ibiblio hosts a few recording archives as well.
The Pandora Records archive contains classical music from Pandora Records, organized by instrument. Recordings can be found under the mp3 and vorbis links. Pandora Records was extant for about 10 years, starting in 1973.
At one time we hosted the Goldband Recording Archive for the Southern Folklife Collection – now hosted at their own site here. Goldband Records was based in Lake Charles, Louisiana and was active in the 1930’s and 40’s. This archive is real treasure trove of photos and recordings from the era in country and western, cajun, and swamp pop music.
Some notable examples of what you can find there
Dolly Parton recorded her first original song “Puppy Love” at Goldband.
Cajun accordion of Moise Robin – Here’s a great interview with him from 1980.
Recordings of Phil Philips (Swamp Pop legend who wrote Sea of Love) singing Stormy Weather and Take This Heart. https://dc.lib.unc.edu/cdm/singleitem/collection/sfc/id/40937/rec/1
Katie Webster’s Don’t Drive Me Deeper
Fats Domino’s Blueberry Hill
Fats Domino and Dave Bartholomew’s Ain’t That a Shame
Fats Domino and Dave Bartholomew’s Valley of Tears
Dave Bartholomew’s Blue Monday