While I can't say I know too much about the old music of eastern Europe, I know for a fact there was more to it than military marches and hymns about loyalty to the motherland.
This Yugoslavian song, which mocks the USSR, is a prime example of it. I believe it even won some awards for alternative rock.
Now Yugoslavia in general is an exception, but I have no doubt that every country of the former Warsaw Pact had an elaborate musical culture. I know for a fact Russia did. This thread is for the citizens of those former Peoples' Republics (I'm thinking Poland in particular given the number of Poles here) to show off their land's best.