I was excited when I saw that someone had made a graph of the influences among philosophers, but I'm a little less excited after looking at it. First, the graph, which is cool enough -- you'll have to click on it to see anything but "Plato" probably -- but then the reasons for my mild disenchantment:
This graph was constructed according to the "influenced by" section for philosophers on Wikipedia, by the method here. That's a pretty nifty (and easy) way to get a graph. But I'm not convinced the lower levels of this network have enough reliable data that they say anything. Granted, I have my own biases, but the philosophers I know anything about don't really fall in a place that illuminates anything about them. There's a distinct lack of the Christian philosophers I know best (John Calvin is way out on the edge, which I just know is wrong), so I think this graph has suffered from the biases of Wiki contributors and artificial distinctions between theology and philsophy (for some reason, Muslim theologians are more commonly classified under philosophy by Wikipedia, see the northern part of the graph). Alasdair MacIntyre by Augistine of Hippo makes sense, but what are Francis Bacon and Muhammed doing there? Ayn Rand by Richard Swinburne? I'm probably trying to stretch the graph too far, but to me that's just the point -- this graph can't be stretched very far at all. It shows interesting relationships for the top 10 names is all.
I just don't see how this really illuminates anything beyond the banal conclusion that all philosophy is connected. It should be able to say more, but it needs more effort on the back end to make it interpretable on the front end. My conclusion is that a simple analysis leads only to simple interpretation, and there's still a role for the human brain in interpreting Wikipedia!