I had tried visiting the World Names Profiler a couple weeks ago, but the interactive map wasn't working for me. Thanks to a tip from Gerard at the Presurfer, I returned today and met with complete success.
When you visit the site and type in your family name, it generates a world map showing the relative frequency of that name per million people, created from a database of 5 million unique names and 300 million names located worldwide. You can zoom each country to a state, regional, or county-equivalent level.
I've embedded the map of my maternal Distad grandparent above, and the "hot spot" is correct down to the correct fjord in Norway. Searching a paternal grandparent allowed me to find the likely point source in Germany, which I had previously not known.