Social graphs show how you are connected to other people, and who they again are connected to. This is hot in the social computing, and can easily show who's connected to who. Now there is a set of .NET classes and a Excel template for network graphs available on codeplex. It is delivered by a team from Microsoft Research.

Check it out at http://www.codeplex.com/NetMap 

 

Just some samples of what you can get:
Graph3Graph12