This site gives maps with the relative and absolute distribution of surnames. I found that there are no longer any Friebels in the area that mine came from (maybe they all came here . I'm also using it as a starting point for an ancestor who I only know they are German, but don't know where they are from. It's not a common surname so I'm hoping that seeing where they are now will lead to some finds (or at least a starting point) on where they were.http://christoph.stoepel.net/geogen/en/Default.aspx#
I looked in the German Roots Project resource pages and discovered that no one had documented this information there yet (or if they did, I couldn't find it), so I created a new free-space page about these and other "map your German surname" resources. The page title is Finding Geographic Distributions of German Surnames.
The page privacy level is Open because additions are welcome!
Great resource. Thanks so much.