One of the suggestions in 5BucksADay is to create sites based around certain subjects, then monetize the site by adding affiliate links. This jibes with an affiliate marketer I met at a local Web Designers Meetup who told me that all he does is create a site around a certain subject (his example was "Canadian Pharmacies"). He would then add SEO content, affiliate ads, and connect to 1-2 blogs that already write on the subject (he said he didn't have the time to maintain 100 blogs). He would then rinse and repeat. Because Search engines love new content, the blogs were key. If he got $5/day, that was great, because then he could duplicate that success 100 times.
I found a book on Amazon that seems useful: The gist of it is a method of using Google adwords as a way to market affiliate programs. It is step-by-step and is a hands-on method of creating an affiliate driven business. I highly recommend it. He claims that he became a millionaire by using the methods he describes in his book. I think it's probably possible, but the learning curve may be a bit costly as you navigate the intricacies of google adwords, but I think if applied correctly this may work.