Amazon debuts Kindle Unlimited on any device for $9.99 a month on Friday debuted Kindle Unlimited, allowing customers to access more than 600,000 Kindle books, and listen as much as they want to thousands of Audible audiobooks for $9.99 a month. Kindle Unlimited subscribers will also receive a complimentary three-month Audible membership from all Kindle devices or with Amazon's free Kindle reading apps.

Is Amazon a digital Walmart? 10:31