Lendle is - was? - a site that let you lend out your Kindle books to other people. You know, much as you would be able to do with other books that you bought and paid for. Amazon actually supports this functionality, sort of. Many of the books in the Kindle store can be lent to other Kindle users one time for 14 days. But that's it. Lendle is one of several sites that have sprung up recently to facilitate this. But yesterday, Amazon shut down Lendle's access to the API (application programming interface) for Kindle, meaning that it's that much harder to lend books and that much more necessary to purchase books at full price.
Look, the Kindle is a popular device. Lots of people got one for Christmas. The e-ink is cool. Everyone's happy. But make no mistake: YOU DON'T OWN THE BOOKS YOU PAY FOR. All you're doing is licensing the books for particular purposes. They aren't really yours.