Systemantics: How Systems Work and Especially How They Fail, John Gall. Pocket Books, 1978.
Peter Coffee recommended this in his keynote at Agile ’06, and I can see why. It’s a humorous look at how systems are by nature out of control. My favorite rule – “A complex system that works is invariably found to have evolved from a simple system that works.” (Reviewed August, ’06)