|Image from The Book Depository, Powered by Google Maps|
But such systems are coming of age with the likes of Google Maps making it easy for companies to pump data into a map, providing a visual representation of that information.
As an author, I find a particular fascination in the application set up by the online bookseller The Book Depository. You can watch in near-real time as book sales ping up around the world. (Rather confusingly, after the initial sale they seem to go backwards in time, but hey, no one's perfect.) Who is buying what, and why? See the Compedium of Crochet Techniques followed swiftly by The Legend of Zelda Vol. 10. Yes, they're all buying deep literature or stimulating non-fiction. But seriously, it's downright hypnotic. Take a look.
Thanks to Martin Daniels for bringing this to my attention