I am not sure if it's relevent, but if you are interested in Rammstein and Oomph you could join this new guild I created and invite people to join.
I have not listened alot of other music in german, a bit of megaherz maybe but mostly Rammstein even Oomph I am a bit of a noob with but Rammstein has become pretty much my favourite band in existance.... yeah i'm so cool...
As for other metal bands I love black sabbath along with ozzy. Some NIN and perhaps even The Birthday Massacre... but all of which are english
Oh and don't forget the band that Richard Kruspe started from Rammstein called Emigrate... also the bomb! <3