A 1947 Lux Radio Broadcast of It's a Wonderful Life with original cast (Jimmy Stewart et. al). MP3 Link, hour-long, 10meg file.
Reader comment: Greg Tulonen says,
Thanks for the It's a Wonderful Life link. Lux Radio Theatre was a curious and wonderful show wherein the stars of major motion pictures recreated their roles for a live radio version (with no retakes!) It ran for over twenty years, from 1934-1955. I can't imagine the movie stars of today agreeing to a similar arrangement with television.Reader comment: Kim says,
The great otrcat.com offers mp3 CDs of every Lux Radio Theatre episode ever broadcast, as well as hundreds of other radio shows: Link
You know that the film used to be in the public domain? It was copyright free from 1974. Then in the early 90s, all prints and underlying elements got bought up by Republic Pictures; stopping the free-to-broadcast showings on US TV? Shame, isn't it? Link to Wikipedia entry with history.