The Long Tail started as an article in Wired magazine in October 2004 which Chris Anderson went on to expand into the book that was published in 2006 by Hyperion. It was recomended to me by someone at an SEO conference recently and I can't put it down. Lot's of good info about e-commerce. :) Are there any other good e-commerce books or SEO books that aren't obviously SEO related?