What programs have you used thus far? Also, how are you approaching affiliate marketing? Are you trying to build a empire on PPC campaigns or search engine marketing?
I ask all of this because what worked for everyone else may not work for you. I mayself have made a lot of money doing search engine marketing. Not to say the PPC is not good, I just don't concentrate on that. In terms of programs, I love eBays affiliate program through CJ. My style is to build for long term. That means build websites that are heavy on content that will last.
So, once again how are you approaching affiliate marketing. A lot of this business is trial and error and on occasion you will strike out.