[igraph] Maps and Networks

[Lorenzo Isella]

Dear All,
A question on the visualization side of network; from time to time we 
all happen to see geographical maps (e.g. air transportation) with a 
network overlaid upon them (e.g. links between London, Paris, Berlin and 
Rome, just to consider Europe only).
I tend to use igraph under R and ggplot2 for statistical visualization, 
but how can one generate some good looking visualizations mainly by 
scripting only?
As of now, I would not know even where I can fetch the maps (let's say 
Europe) for the task, let alone overlay a network upon them.
Does anyone have experience with this kind of visualizations?
A self-contained example even with fake data would help me a lot.
Best Regards

Lorenzo