"The other day, I got an e-mail from Amazon.com telling me about a new Internet marketing book they just got in stock.
They knew I might be interested in it because I'd bought other Internet marketing books from them before. And I was interested in that new one, too.
In fact, as soon as I got the e-mail, I immediately clicked through to the site, checked out the book and bought it. And in doing so, I boosted my lifetime value to Amazon by another 20 bucks."