Dear Gary,
I am also interested whether there might be godparent traditions in the Lutheran way that might help with research on another line of my family.
I have read that there used to be naming traditions in Germany. After the husbands, father, wifes father..etc. Forget exact particulars. I think Family search might have an article about that.
I have noticed in the catholic records from Shrine of St. Joseph here in St. Louis that in my family the child being baptised often seems to be named after the baptismal sponser, or at least one of the childs given names more often than not (in my case). Some of the sponsers were family of the parents, but unsure if all sponsers were actually family members, got alot more researching to do..and as we all know..hard on the eyeballs 
Possible they all were related but not proofed.
I will have to study the record of my known family members a bit more and see if there seems to be a system in the order they picked sponsers, though the order or system they used, (if they did) wouldn't prove one way or the other if there was a system, but if familiar with various families one might deduce something perhaps.
Barbie
St. Louis