Yes, we were looking at ways to use the Kindle library that they already have. But Audible books are compatible with Kindle and they also have an Android app. Of course you're limited to audio the pricing is going to mostly be higher.
I'm amazed with the Kindle how many good books there are for free or really, really cheap. Lots of authors I had never heard of before and now I really like. I've gotten away from even thinking about the NYT best seller lists - there's a ton of good authors out there.