We just activated our 30 day free trial of Audible.com and I love it.  My daughter can listen to digital audio books on her Kindle (the basic one) or my Kindle Fire.  I downloaded The Secret Garden for her first.  She had attempted to read this book before, but found it uninteresting, however, she is loving the audio book.  She and her sister sat and listened together.  I wish that the text displayed with the audio, but it doesn’t.  Since it is digital audio you could listen on a phone, ipod, or any other digital player.  Garmins and TomToms are even listed as compatible.