This is a thread after my own heart! I love finding out and reading old, less well-known and thought provoking books on a variety of subject matters. I have come to the conclusion that "popular" almost always equals "lowest common denominator" and "fad of the month" particularly given today's media hype cycles. Moreover one has to guard against having ones mental models bounded within a box. By actively seeking out lesser known and out of the way viewpoints one truly grows. Some books from my collection which i have not seen mentioned here (in no particular order or categorization);

* The Natural History of Nonsense by Bergan Evans

* Programming on Purpose, Essays on Software Design by P. J. Plauger

* Management: A Political Activity by Ted Stephenson

* The Energy of Life: The Science of What Makes Our Minds and Bodies Work by Guy Brown

* Patterns for Time-Triggered Embedded Systems: Building Reliable Applications with the 8051 Family of Microcontrollers by Michael Pont.

* UNIX Systems for Modern Architectures: Symmetric Multiprocessing and Caching for Kernel Programmers by Curt Schimmel.

* Maxims and Reflections (Ricordi) by Francesco Guicciardini

There are a bunch more i have to root around for :-)