This weekend I've spent a little time playing with the mapping and transitions in D3, as I have an idea of somewhere I could use them on a project. Anyway, I've got as far as this tonight, which takes a csv of countries and values and displays different levels outflow from the UK, with a nice animation as it loads...

So in the example data here I have "France: 3, Russia: 6, South Africa: 2, Australia:10".