Same as amaebi, variable stuff that travels with. Books, articles, study/refresher material if we're on the way to doing a demo. Usually whatever fiction book we're working through -- since L and I usually travel together, I'll read aloud for part of the trip. I used to have a book on tape that I liked listening to bits of as I went to/from one of my old jobs... I should dig it out to listen to again -- Instructions to the Cook: A Zen Master's Lessons in Living a Life That Matters, by Bernard Glassman and Rick Fields.