... until you come to actually turning those results into locations. I've been playing with the Google Maps API and managed to get it working over the weekend. It's currently only available on the development site but it should make a reasonably cool addition.
I've also been playing around with VIN numbers. Theres a fair amount of data you can get from these if you know how to read them. Since I'm getting a large number of international visitors and it'd be another useful addition to have I've started on my own decoder. So far I've got continent and country nailed down, but really need a comprehensive list of WMI numbers (which represent manufacturers) to get myself off the ground. I've found a few sources so I'll have to see how it goes.