I compiled a whole list of German bands singing in German after a similar question was asked some time ago. Please have a look here: http://www.italki.com/knowledge/contribution-Deutschsprachige+Musik.htm Unfortunately this list is rather incomplete regarding certain styles of music such as soul, swing, hip-hop and others. Look also for Xavier Naidoo, Fettes Brot, Söhne Mannheims for instance. Here is the link to the previous question plus answer: http://www.italki.com/Answers/question/28182.htm

I know the bests Metal bands: Scorpions, Helloween, Gamma Ray, Edguy, Blind Guardian, Grave Digger, Destruction, Rammstein....Try to search about Wacken Open Air! good luck!

I think Scorpions are Germans. The one who sung "Wind of Change". I love this group.

I think it's "Tokio Hotel" but I really do not like this band!!!

This lists are an good entry point. If you have an "last.fm" account you can search for this music and hear it. You will receive recommendations from similar artists and also have a good feedback how popular this music is in Germany.