Amazon’s Whispersync for voice was always an interesting curiosity: You can read a book on your Kindle, seamlessly switch to the Audiobook version, and then switch back again, all without losing your place. This works thanks to the fact that Amazon owns Audible, the biggest audiobook seller around.
The service just got a lot easier to use, thanks to a doubling of compatible titles, and a new Matchmaker service which automatically pairs up any books you already own, and lets you grab the audio version for a big discount.