Connector (social) - Wikipedia, the free encyclopedia
"Connectors usually know people across an array of social, planes, cultural, professional, and economic circles, and make a habit of introducing people who work or live in different circles. Although connectors are rare -- only one in several thousand people might be thought of as a true connector -- they are, like mavens and salesmen, very important in the healthy function of civil society and business. Connectors are also important in trendsetting."
See also:
http://en.wikipedia.org/wiki/Weak_ties
"In 1973, stimulated by the work of Rapoport, the American sociologist Mark Granovetter's published The Strength of the Weak Ties. This is recognized as one of the most influential sociology papers ever written."
Not entirely dissimilar to my theory of social triangularity...