Who has found information about my family ?    

The second powerfull site to search in France is CousinsGenWeb : http://www.francegenweb.org/cousinsgenweb

CousinsGenWeb is more acute than Geneanet but is only for French speaking people

Here are some explanations to use CousinsGenWeb.

CousinsGenWeb

CousinsGenWeb gives crossed references between people who found the same family names in the same cities.
But the data are gathered by departments or subregions. 
Unfortunately you have to speak French to use it. But it's easy to understand.

The first step is to select the department you want to study. You have to use its code (from 01 to 95).
If you don't know this code, you can  click here to get some help.

Then you come to the site specially dedicated to the department you selected (Here 57 = Moselle).
The sites are very similar and look like this :

Presentation is a explanation about the site
Les genealogistes gives you the list of the people who gave their data to this site.
Patronymes etudies gives the list of the family names registered in this site.
Communes etudiees gives the list of the places where data were found.

Here are some examples :

To see the family names, which are very numerous, you have to preselect in the table like this. For example if you're looking for Bettinger, you have to select from Beitz-Bentz.
For each family name the table shows the place where data were found and the name of the genealogist who found the data. "Commune" means City.

Here we can see that the Bettinger surname was found in many places by many people.

At the bottom of the table you find the list of the genealogists.

If you want to search by place (which are very numerous, too), you must first select a range of places in the table.
Here we're looking for Freistroff and we select from Eguelshardt to Haboudange.

For each city, you will find the name of the people who found data in this place. For example for Freistroff :

At the bottom of the table you can find the list of genealogists and links to their e-mail.

For more information about the genealogists, you can read the table and get their e-mail and web-site.
Many French people speak a bit English and will be happy to help you in your search.