For many years now, I have used background music in my roleplaying game sessions. Music is a prefect tool to help to set a certain mood. For my last Trail of Cthulhu game, which was set into the late 1930s, I used a mix of movie soundtracks (especially the “A Nightmare on Elm Street” soundtrack works great for any horror game) and 1930s jazz music. I didn’t own any 1930s music, so I had to lend a few CDs from a friend who’s a big fan of jazz music.
But now I found a free source of music from the early 20th century (thanks to the Propnomicon blog). Archive.org has thousands of recordings from 78 rpm records and even phonograph cylinders.[audio:http://ia341010.us.archive.org/2/items/1920s-bigBand-abeLyman-01-10/AbeLymansCaliforniaAmbassadorHotelOrchestra-FarewellBlues.mp3]
The above song is 1920s big band music performed by Abe Lyman and his band.