If you have any mild interest in genealogy, then check out this name checker application. You enter in your surname and it reports back to you the places in the world where your last name is most popular. Mine showed some surprising results – for a French last name, there aren’t any listed in any French speaking places! The US has the lion’s share, which wasn’t exactly unexpected. However, apparently there are a lot in the UK and Argentina. Who knew? If you click on the map and drill down, you can ultimately get to county level data (or equivalent) for much of the world.
Be warned, however, their data is questionable. They say the data comes from telephone directories or election registers from 2000-2005. However, there are no people listed with my last name living in the place I’ve lived for the last 8 years! So at least one data point is missing!