There is a "Karten zum namen" or "map for names" page that appears to use phone book records and then map the frequency of a surname by district or city. While this may not be the most accurate source of information for researching my ancestors, I was able to find some interesting current geographical areas for surnames.
I started with my paternal great-grandfather's surname of SPECK, which was not very helpful as it is a more common surname (as well as SPECHT, which I also searched). Below is the map that was generated for SPECK:
When I searched for my maternal grandmother's GEGENHEIMER surname, I found a more interesting picture:
The website has the following (translated) information below the map:
"Statistics: Figures on the surname 'Gegenheimer'
In Germany there are 163 phone book entries with the surname Gegenheimer and approximately 434 persons with this name.
They live in 32 cities and counties. Most occurrences are in Karlsruhe, namely the 73rd
Other counties / cities with lots of occurrences are Enz (22), Karlsruhe (10), Pforzheim (8), Alzey-Worms (7) Berlin (4), Böblingen (3), Stuttgart (3), Lahn-Dill circle (2) and Mannheim with 2 entries.
Stefan Gegenheimer occurs in Germany most often. Ruth and Anke are the next often found first name, followed by Luis, Rainer, Adolf and Werner."
I have located church records that go back almost 300 years for my Gegenheimer ancestors in the small village of Ittersbach. Ittersbach is in Karlsruhe, which is one of the red areas above, indicating that there are still many Gegenheimers in that area.
I found other similar maps for other surnames, but the most fascinating was the following map for the surname of my paternal second great-grandmother NILKOWSKI:
"Statistics: Figures on the surname 'Nilkowski'
In Germany, there are 11 phone book entries with the surname Nilkowski and approximately 29 persons with this name.
They live in 3 cities and counties. Most occurrences are in Dortmund, namely. 8
Other counties / cities with lots of occurrences are Unna (2) and Solingen with 1 entries.
Corina Nilkowski occurs in Germany most often. Alexandra and Klaus Dieter are the next often found first name, followed by Peter, Uwe, Christa, Angelika and Michael."
There are very few NILKOWSKI hits, which is not surprising as it does not sounds like a German surname. Through her German marriage record, I have learned that in 1865 Elisabeth Barbara Nilkowski was born in Muensterberg, in the district of Marienburg, which is in current-day Poland.
Elisabeth was living in Gelsenkirchen at the time of her marriage in 1886, but her parents were still in the region of Braunswalde (also now Poland). I have wondered why a young unmarried woman would be living so far from home and wonder if possibly she lived with another family member. Dortmund, the region in red, is only about 20 miles from Gelsenkirchen. Could these few Nilkowskis in Germany be related to her?
This website also has options to search for surnames in a few other countries including Poland, Great Britain, France, Argentina, Spain and others. I did have some problems getting results with several of these countries, but had success searching in Poland.
Again, while this is nothing more than information pulled from a phone book, it was interesting to look at the distribution of current day surnames as compared to where I have any records for those ancestors.
Gelsenkirchen, Nordrhein-Westfalen, Germany, Marriage Record no. 195, Christian Fasel-Elisabeth Barbara Nilkowski, 1886; Institut für Stadtgeschichte [Institute for Urban History], Gelsenkirchen.