Seth Godin has to be one of the most forward thinking marketers around, what ever he writes is worth reading. He has authored books such as The Purple Cow, Permission Marketing and more lately, Meatball Sundae. You can get one of his books FREE, in ebook format. To download his manifesto on viral marketing and idea viruses click the link. This has been out there a while but I only came across it recently and enjoyed it thoroughly.