I really like audio books. And downloadable audio books are a good idea. However, for people (like me) who are limited by that pesky dial-up connection, this technology is also difficult to utilize. So, for the sake of this exercise, I just pretended I had a fast internet connection and wanted to download some audio books. :-) I first visited Project Gutenberg, which I felt left a bit to be desired. I couldn't find any of my favorite authors via the author search, so I assume they don't have them. I then cruised over to Netlibrary, where I had much better luck. I found a few books by Anne Tyler and Julia Alvarez. No Amy Tan, Margaret Atwood, or John Irving, though. So I suppose if I really wanted any of those authors on talking book, I'd need to visit the library!
As far as selection goes, Netlibrary seems to be better than Project Gutenberg. So if I really was going to try to download a book, I'd probably go with Netlibrary.