I've created a free search engine for Mennonite genealogy. It indexes Mennonite obituaries, censuses, immigration, cemetery, and such from relevant sites across the web.
It was launched last month. It's called MennoTree. Its at http://mennotree.com
It contains both Prussian/Russian and Swiss Mennonite lineages, but there seems to be much more available on the Prussian/Russian side.
Hoping for feedback.