Here are the ones I came up with; if anyone knows of more, let me know and I'll add them to the list.
1. Tolkien's own recording of the scene with Gollum. Wonderful. If only we had a recording of him reading the entire book. But this is v. much a case of counting our blessings, and marvelling over our good luck that he made such a recording, and that it has survived, and been made available to us (orig. on Caedmon Records, since re-released in various compilations and formats).
2. The Mind's Eye radio play. By far the best adaptation of THE HOBBIT ever, into any medium. The same cast later did a LotR that is unfortunately not nearly as good, but their HOBBIT is the Gold Standard. Thorin's abilities as a leader throughout the long journey particularly come across in this version.
3. Nicole Williamson, for Argo Records. Wonderful, but unfortunately abridged. As I understand it, N.W. recorded the entire thing but the record company decided to cut it down to a four-album set. I've always hoped that the deleted bits survived and might be restored someday, but if so there's no hint of it. And Williamson himself having since died, there's no chance he might make a new recording of the whole. Alas.
4. Martin Shaw, for Durkin-Hayes. Well done, but unfortunately abridged. The abridgment is skillfully done: if you don't know THE HOBBIT well you'll never notice it, but the better you know the story the more you miss the little bits of dialogue and observations by the narrator that were trimmed. On the plus side, Shaw does a good job with the reading, and it's interesting to hear THE HOBBIT with a non-posh accent
5. Rob Inglis, for Recorded Books. Uninspired (I find Inglis's voice too monotone for a long story), but has the virtue of being the sole complete recording; all the rest are abridged or adapted. Maybe we'll be lucky enough that the films will be so popular as to cause a new recording to be made by the likes of Holm, McKellen, or Freeman. We can dream, can't we?
7. Not sure if this really counts or not, but the soundtrack that was released in conjunction with the Rankin-Bass HOBBIT as a two-record set is in fact an abbreviated version of the whole story, with narrative between the songs (and this version was notable for including most of the poems, sung with gusto to Tolkien's original lyrics).
8. Finally, there's the 'text-to-audio' feature on the Kindle. Aesthetically it's dire, but it has the virtue of giving you the entire text just as Tolkien wrote it.
. . . Or at least that's how I remember them. Now to find out how well my memory matches up to the reality, or how much my response may have changed since I last listened to them.
current reading: Lemony Snicket (ALL THE WRONG QUESTIONS), Margaret Atwood (TRUE STORIES)