Poland - Polka (traditional) or Riverside (modern/rock)
Hungary - I dont know
Spain - bullfighter type music or mariachi band?
Scotland - Bagpipes! Some Celtic Rock .. stuff they play at "scotch festivals" or "highland games" ... Example: Mud Men (yes they come from Canada, but doesnt matter they are awesome). Otherwise, there is always Pirate Metal, Alestorm.
Sweden - play some traditional Yoiking, or just stuck on some Opeth or Katatonia, their newer albums are more accessible to non-metal people...
Russia - Tetris soundtrack!
Germany - More Polka!
Greece - I dont know much greek music