Not Zen or anything, but "The Prince" by Machiavelli is also great Evil Emperor strategy guide, and also short.
More on-topic would be "Jonathan Livingstone Seagull." Also short. I don't agree with its underlying philosophy (reincarnation), but I liked how JLS kept striving to be better. Supposedly Winnie the Pooh is Zen-like, at least according to "The Tao of Pooh." And physics is Zen-like, according to "The Tao of Physics." Personally, I think you'd be better served by just reading the Pooh books and studying physics.
