Personally, I'd love to have fics in MP3 format. I listen to Podcasts/audiobooks/etc at work all the time. I'm currently on chapter 7 of DH and have Pottreficweekly's (which I'm listening to as I type) Mugglecast's, and HP Prognostication's latest episodes to listen to. I know that Spellcast does fic readings once a month, too.
As for the no need for the beta if it's in audio format.... I don't think that's true. You may not need someone to correct spelling since nobody's going to *see* it, but having correct spelling and punctuation helps the person who's reading it to be able to pronounce things right, and to pause in the right spots...makes it easier to understand and listen to. You need the voice inflection to know if things are a question vs a statement vs an exclamation (? vs . vs !). Betas would help with that. Plus, my job as a beta isn't only to correct spelling and grammar. I also watch for/point out plot holes, awkward sentences (they'll still sound awkward if it's written awkwardly), characters acting out of character, whether there's not enough or if there's too much description in a passage, if there needs to be dialogue tags so we can tell who's talking and what he's doing, etc... The spelling and grammar is a *small* part of the whole beta job, at least for me.
Also, there are a lot of people who would rather *read* a story than listen to it. I think most authors would write for people to read, but then might add their fic so people can listen, too. That's how I would do it, at least.
Would you have a place for feedback? And a way for the author to respond? Feedback is very important to most (if not all) fic authors.
Does that help?
~Julie
--
If you haven't got any charity in your heart, you have the worst kind of heart trouble.
~Bob Hope