I wrote a graphical frontend for the Unix traceroute utility, using the Processing API. traceroute uses the TTL field in the header of IP packets to determine the route a packet takes on it's way through the network jungle.

I parse the output of the traceroute command, determine IP addresses for the hosts and resolve geolocations using a GeoIP database. The results are then mapped on a sphere.

The project makes use of the great libraries toxiclibs, controlP5 and GLGraphics.

The source code is freely available via GitHub:
github.com/cmichi/visual-traceroute/

More technical details can be found here:
ioexception.de/2011/09/18/graphisches-frontend-fuer-traceroute (in german)
micha.elmueller.net/2011/07/visualization-traceroute (in english)