I was just looking at the great gnuplot program, and saw how they are using it to take nodes from GPS data, to create XML files of latitude and longitude, and then feed that to gnuplot. See maps with gnuplot

I'm sure the learning curve is easier with Graph::Viz, but gnuplot is worth looking at. You could set up a world map of latitudes and longitudes of each net node and plot it. Gnuplot can output svg too, which is a nice feature.

P.S. If you want to, you can process that huge planet.osm file with PerlSax.