Very cool way to present this. Obviously there's a lot of legwork here, but for major ISPs you could probably use some heuristics to give a little more detail on internal network structure. Comcast, for example, has their core network under ibone.comcast.net, but their HFC infrastructure directly under comcast.net. So you can tell when traffic makes the jump from their HFC consumer ISP network to their backbone. At one point I had some notes on patterns like this for a number of the majors but I think I've lost it. :(
