Network Marketing is powerful because, when done right, it allows customers to spread your market influence and advertise to others. This article explains how social networks, in particular, are powerful tools to reach and sell to new customers.

Network-based Marketing: Using Existing Customers to Sell to New Ones

Marketers have long used all sorts of demographic and geographic data to target potential customers — age, sex, education level, income, zip code. But there’s another variable that companies may want to consider: Who is connected to whom?

http://knowledge.wharton.upenn.edu/article.cfm?articleid=1637