Can someone uncover the design process behind social network visualisations such as http://inmaps.linkedinlabs.com – and how those interconnecting Béziers are generated?
So those kind of network graphs are often called node link diagrams. This article might be a good place to start: The Links That Bind Us: Network Visualizations.
There are also pieces of desktop software that generate them without code and that often allow the nodes and links to be dragged around. Maltego Casefile is one free example. These tend to be more useful for aiding research and for rough 'data sketches' than for final designs, but they can be a handy tool.
Some of these can plug into social networks or parse email files directly: otherwise, you'll need to look up the appropriate API and do some coding.