This 2009 "subway map" of the Internet is based on Tokyo's subway system. This design company (like a few others, I think) does one of these every year. It's a articular genre of a thing called an "infographic" that you see everywhere.
Mapping the Internet is actually a very popular thing to do. See also this "subway map" of the Internet mapped onto Tokyo's subway system: http://ia.net/blog/web-trend-map-4-final-beta/