When I was about 7 years old, my Dad brought home a collection of audio tapes that contained the 6.5 hour 1981 NPR broadcast of the radio version of Star Wars. Adapted by novelist Brian Daley, this series provides a rich back story to the original movie. Its' sound effects, musical score, and craftsmanship have been called the most ambitious radio project in history. As a boy, I listened to these tapes every night before falling asleep.
And now the entire series is available on 6 CDs via the NPR store. This one is well worth having.