In an analysis of search engine and social media sites, Facebook was shown to have the most loyal visitors in terms of browsing habits. The study done by the ad network Chitika studied browsing habits of the top SE and SM sites in the month of September. What was really surprising to me is that Digg came in second and Yahoo a close third. Bringing up the rear were Google and Bing (tied for fourth) and Twitter in last. Here is the link to the study on the Chitika website
http://chitika.com/research/2009/digg-facebook-loyal-readers/