FamilieNaam.be is a Belgium surname mapping site. You can type in a family surname and the site will map the number of occurrences of that surname on a current map of Belgium.
The maps are based on Belgian population registers from 1998 and 2008. You can select which year you’d like to search. The darker a municipality appears on the map, the more frequent occurence of a given surname. Visit their instruction site for more helpful search tips.