Oh, Kindle does have a way to share books, but it's limited and complicated in other ways.

Using my brother's situation....he has a kindle and an amazon account. His in-laws have Kindles and an account. If his MIL buys a book that he might find interesting, he can take his kindle "off" his account, put it on MIL's, and download the book. He can then read it. Once he connects to his account again, the book will be gone, but unless you get daily downloads each day, you really should keep the connection off to save battery life.

This gets complicated b/c if you forget that you're on someone else's account and buy a book, you're using THEIR money...so you have to get your kindle off their account and connect back to yours before you want to buy more books.

You can have something like 6 kindles on your account.