Lateral Thinking by Edward De Bono (1990, Paperback, Reissue)

I already had a copy of this book and bought a second copy to share (without the risk of losing my only copy.) De Bono sets out the case for the sort of creativity that can be taught. This "Lateral Thinking," far from being a replacement of modern society's "Vertical Thinking," is a method of generating ideas that otherwise would never "make the cut." It's a tough read -- I worked through it over 18 months -- but worth the effort.