don't know if you know the DAAD yet? Its the main address for international students who wish to study in Germany & for German students who wish to study abroad. They also have a database of scholarships for foreign students on their web page:
Its sorted by degree, country of origin etc.
Remember that in Germany, there are many associations and foundations that give scholarships to special groups of people; e.g. members of a specific social group, minority or religion, people who have done voluntary work & have special interests (environment e.g.) people with handicaps or special kinds of diseases, etc. There also exist some scholarships for acknowledged refugees!