While Amazon has been around for 15 years, the Kindle and Kindle store have existed for just under three. Amazon credits the success to lower prices for the ebooks (many, even new releases sell for just $10), and the availability of out-of-print books in the Kindle store. Additionally, the recent price drop and wider availability of the device and a number of mobile apps have made the store a popular entertainment destination. Are you on the Kindle train? Tell us how many books you download on a regular basis in the comments!