If you haven't heard of or checked out Skimlinks yet you should. Basically they take care of all of the hassle of managing multiple affiliate sites/links for you and automatically convert outgoing links into affiliate links for you seamlessly in the background. I have used affiliate links for a while and have really only had success with Amazon Associates. Skimlinks is a great addition that cuts out work for me trying to sift through individual affiliate programs. Its free to sign up and they make their money by taking a small cut of your affiliate percentage, which I think is worth it because of all of the time I save. This basically takes over the use of the URLrewriter add on here and instead of only working for like 5 sites, it works for 17,962 merchants. This is a great way to monetize your site without adding additional ad blocks that clutter up the place.