Also, this guy documented his trip from Vienna to Pyongyang, North Korea: http://vienna-pyongyang.blogspot.com/
Several hours before midnight, the coach I was in started morphing. Normally people didn't really talk to each other. That night, seatmates started talking, impromptu cardgames were started, I was certainly not the only one with hidden alcohol, and the bar was providing plenty for those without. By midnight the car I was in, and the adjacent car with the bar, were in full party mode. It was simultaneously one of the most surreal and awesome trips I have ever taken.
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As for the Amtrak writer program - very cool. As a young serviceman, I would frequently catch a Friday night Amtrack away from the military town I was stationed in, picking a random location that I could spend Saturday in, and then ride back Sunday afternoon. I didn't write about or photograph my travels (wish I had), but I can't image a writer worth their salt not being inspired by the scenery, events, or people met on such random jaunts.
One tip: if you're thinking of making the journey, bring a small hose with you so you can hook it onto the sink and have a little shower. Also, there are companies that will arrange home stays if you want to get off in Yekaterinburg or a few other towns and kick around for a bit.