I'm sitting on the platform at the main Prague train terminal, waiting for the train to Berlin. As biting wind blows across my neck, I look down at my sandled feet, and start to regret having packed only apples for the two week trip. I could use, perhaps, a thick jacket or a pair of socks or a change of underwear. But its not a huge problem-- the European rails run on a barter economy, and apples are barter gold. I arrive in Berlin with several pairs of underwear, a fancy leather jacket, a warm feather boa, and the first three seasons of Seinfeld on DVD.