One of the common complaints with affiliate programs is that it takes a lot of work. Even if you are already linking to your favorite Amazon book, to benefit from that you need to sign up, be approved, install the link tracker etc.
A new company named VigLink seeks to make this a lot easier. They automatically scan your site for potential links and then automatically can set you up. They maintain accounts with all of the major affiliate programs meaning you don't have to.
They are pre-launch as of now, but you can still get a site report right now.
Check them out at VigLink.com