Jonathan Volk is a very successful affiliate marketer (makes US$4 million a year) but I have never heard of him before. It goes to show you how big the market is. Anyway he is offering a free Affiliate Masters Course is one of the first few free ebooks I read. No hype, no fluff and highly recommended. It’s written by Dr Ken Evoy. I am an affiliate of Sitesell.
I do think they are great for beginners and even folks with years of experience would benefit from it too.