While I never considered myself a rabid Star Wars geek (I don't have the trivia game, any apparel, or any of the books or comic books), I happened upon the Star Wars Radio Drama done for BBC Radio back in the early 80s, and was impressed at how well the story translated to the audio-only medium. I bought the Empire Strikes Back and Return of the Jedi audio editions, and was similarly impressed. These were done with full casts (including Mark Hamill and Anthony Daniels for all three), full sound effects, and full production teams, and they did a great job recreating the feel of the movies.
Hooked, I proceeded to get my hands on audio versions of the Star Wars books. Ironically, I never enjoyed reading the books....I started a few, and never got more than a few pages into it before I got bored. The audiobooks, however, even those with a single reader rather than a full cast, were fantastic, especially for those long-ass drives. As I tried to amass my collection, I found that it was very hard finding out which books had been translated into audio format, there were limited complete lists out there.
So here it is. Every audiobook I know of. In chronological order occurring in the Star Wars universe, with Year 0 corresponding to Star Wars Episode 4: A New Hope (in the canon, the specific Year 0 event is the Battle of Yavin). Most of these are still commercially available. If anyone out there knows of more, please comment below, so I can add it to the list, and my collection.
Lastly, I've got links to the audio for a few "read along books" below (Planet of the Hoojibs, Droid World, etc.). If you would like to download complete books with audio in Flash format, visit Read Along Adventures.