What do you think this is?

Gabriel Syme ("Colourful web") of Samizdata links to it, and explains:

A project to create a comprehensive graphical representation of the internet in just one day and using only a single computer has already produced some eye-catching images. The Opte Project uses a networking program called "traceroute". This records the network addresses that a data packet hops between as it travels towards a particular network host. The project is free and represents a lot of donated time.

Well I didn't fully get all that, but it sure looks pretty.