There are some companies that seem to really love puns. Google certainly does, but so does Amazon. Amazon's new service is called Kindle MatchBook, and it lets you buy the Kindle edition of books at a steep discount if you've bought them in physical form from Amazon at some point in the past. It doesn't even matter if you still have the book, or if you lost it a decade ago. Prices range from $2.99 all the way down to free, but only for supported titles.
Amazon is touting 10,000 books available through MatchBook at launch, with more publishers and authors expected to get on board soon. And why shouldn't they? Getting a few bucks from a lot of people who have already bought the content once is better than nothing. And there aren't too many people paying full price for that Kindle edition when they already have it in dead tree form. Authors like Ray Bradbury, Neil Gaiman, and Oliver Pötzsch are already involved.
Amazon will make it easy to see which of the titles you've bought in the entire history of Amazon are supported. The company will match the books (get it, match-book?) in your account history to the ones supported by the new service. Keep in mind it will only count the books you purchased on your current Amazon account. If you left behind the embarrassing @AOL email address a decade ago, you won't be able to get books from that account on the cheap. MatchBook is going to be rolling out in October to all customers.