This route tip is not really cheap, but worth to be recommended. Between Berlin and Malmö runs the private operated Berlin-Night-Express train. A oneway ticket with a bed to sleep costs 88 € (or 60 € if you are under 26). With a swedish railpass you only have to pay 15 €. Even as this train is private, you can buy tickets at the normal ticket office. The train runs daily until 24/AUG/2008, leaving from Berlin at 23.16 arriving in Malmö at 08.00 the next morning, in the other direction leaving from Malmö 21.32 arriving in Berlin 06.04 the next morning.