We recommend some books and have links directly into Amazon and get a small cut of the sale if you buy it by following the link. Amazon does all the real work, we just provide the pointers.
The man has this to say:
Amazon.com Associates list selected books in an editorial
context that helps you choose the right books. We encourage
you to visit Tropo often to see what new
books they've selected for you.
Thank you for shopping with an Amazon.com Associate.
Founder & CEO
P.S. We guarantee you the same high level of customer service
you would receive at Amazon.com. If you have a question about
an order you've placed, please don't hesitate to contact us.