World Names Profiler holds an enormous database of names:
"We hold data for approximately 300 million people in 26 countries of the world, representing a total population of 1 billion people in those countries. In our database there are 8 million unique surnames and 5 million unique forenames."
Entering your surname will bring up a map in graduated shades of blue to denote the density of population sharing the name. Below the map is more information, such as the root of the name in group and subgroup. Finally, there are lists detailing how many per million live in specific countries and cities.
It's always fascinating to find out where in the world we come from.