I've been unusually fortunate in finding resources that speak to where my surname (Rempel) came from. My first sources were the Mennonite Encyclopaedia and Mennonitische Namen/Mennonite Names (a bilingual book by Victor Peters & Jack thiessen published in 1987). Both are in the MHSA library for anyone to consult.
In addition, however, I located a German-language article published by W.J. Rempel of Goettingen in Ostdeutsche Familienkunde (1960), which Ann Rempel translated, and then I edited it and placed it online. The article is particularly interesting because it delves into the root of the name as a given name and explictly lists many of the early "name-bearers".
What have you found out about your own Mennonite surname (or other Mennonite surnames that you are researching) and what have your sources been? The methods you've used and the resources you've uncovered may well be of great help to others.