I think most people know about this already, but in case you don't ... Here is a collection of public domain old time radio shows. If look on the right side of the window, you should see a link for a bunch of AFRS shows as well. I'll load them on an MP3 player for period background music.
Might be difficult to work this into an event, but here is a collection of videos that can be downloaded and viewed at your pleasure. Some of John Ford's war time documentaries are available as well as PVT Snafu clips.
Anybody else have online libraries they use?