Check-out this article by Heidi Cohen, a writer on the ClickZ Network. She provides terrific insight into "How Blogs Drive More Sales than Social Media Sites."
Below is a list of four great books that I recommend for any digital marketer:Groundswell: Winning in a World Transformed by Social Technologies, by Charlene Li and Josh BernoffSocial Media Marketing, by Dave EvansWeb Analytics, by Avinash KaushikHere Comes Everybody: The Power of Organizing Without Organizations, by Clay Shirky