One place you might check is the Beaver Dam Community Library. They have a local history area and also have a card file for some of the cemetery transcriptions in the county.
You also might want to check with some of the churches in the area. I noticed that your ancestors lived fairly close to my ancestors the Luttenbergers in the 1870 census. The Luttenbergers attended Trinity Evangelical Lutheran Church, at Huilsburg. I obtained some information from them and I believe that the LDS Family History Center has microfilmed the records from the church from 1864-1983.
Perhaps you already know that Gottfried Salzmann and Dorothee Zunke were married at Nahausen, Brandenburg, Prussia on Jan. 26, 1832, according to the LDS website.