Scribd just added about 30% more to their audiobook library. As I glanced through their library, I think roughly half of the books that Bookwi.se has reviewed in the last five years are now available at Scribd in audiobook and/or ebook. (I just added 45 books to my wishlist in a quick browse of the new books.)
I have been a subscriber to Scribd for nearly 5 months now and I have read about 25 books, either audio or ebook with my subscription. I have not used it quite as much the last month, with the birth of my son and because I have been trying to catch up on other books that are not available on Scribd. But I will continue to subscribe to Scribd for the forseeable future.
If you are an audiobook fan and/or if you have a tablet or phone that you use to read ebooks, Scribd is the best of the three big book subscription services. It is $8.99 a month to read or listen to as many books as you can.