A great post on Design Observer featuring the notebooks of graphic designer, design critic, and educator Michael Bierut.
 
Look at the simplicity of the medium. Nothing fancy. Just simple, composition notebooks that you can buy at any store...
 
 From the article: "Like most designers, I get asked a lot about my process. A lot of my ideas are so simple and dumb that a simple dumb drawing is all it takes to describe it."
 
[ source: http://designobserver.com/archives/entry.html?id=38831 ]