On the GOOD website today, this fantastic new mapping of Great Britain (i.e. the UK without Northern Ireland and the Isle of Man). Using phone records (excluding mobile phones), he's built the map of what areas interact with each other – and colour-coded areas that interact.
I love the fact that some geographical boundaries seem to emerge naturally through the interactions, but some of the usual ones don't.
More detail can be found at the MIT site for the project.
Given that they only used landline phone numbers, I suspect that it's excluding some significant groups – landline implies that you've got a stable home, either rented or owned. And, without checking, it strikes me that excluding mobiles means excluding a disproportionate number of students, young people, nomadic workers, etc.