It's a hulking behemoth now, but let's not forget that Amazon got its start peddling books. It never really forgot those roots, either: somewhere along the way it built its own e-reading platform and snapped up a pricey purveyor of audiobooks. Now the e-commerce titan is trying to blur the lines between those two properties even more thanks to a new update to its iOS and Android Kindle apps. The changelog is a pretty lengthy one, but the addition of Whispersync for Voice is the real standout here -- now book buffs can leap between words on a digital page and a professional audio recording without having to leave the Kindle app proper. The upside for Amazon is clear: if it can make it easier for you to jump back and forth between reading and listening, it's got a decent shot at selling more audio recordings. Synergy, folks! If that somehow improves your reading experience along the way, well, that's just peachy too. Just be warned that not every book available from Amazon's virtual shelves has an Audible equivalent -- the company has said there are about 45,000 book/recording matches out there.