Matthew Hurst has some serious social network visualization tools in his hands. Matt is the Director of Research at Intelliseek and co-founder of blogpulse. If you are interested in understanding how people interact online, you should subscribe to his blog, Data mining.

Has latest post points out how important the bloggers are that have influence in multiple spheres of influence. He points out how Om Malik is influential among techies (he's one of my main reads); how Stephen Malkin is influential among socio-political bloggers (I don't even know enough about Malkin to tell you what he blogs about); and how Jeff Jarvis is influential in both spheres (I do read Jeff Jarvis too). I guess I illustrate his point.