Not a very new concept, but it seems that the advertising industry adopts the “Birds of the Feather… buy together” concept now. It’s interesting that very traditional social networking concepts, such as peer pressure, preferential attachment, etc. Studies on who to target to effectively spread rumors in networks have lead the way for effective online marketing – the open question is: how can marketers identify those influential hubs in the network? What if they want to use online social networking services to target specific groups? The number of contacts does not necessarily mean that people are also influential or are perceived as beeing important exchange partners – “harvesting” all potential contacts and randomly “friending” as many people as possible, are not necessarily indicators for successful social influence.