One of my favorites is the Delphi technique. I have actually used a form of it several times in my work before I even knew it was a technique, and I suspect many of you have used it too in an informal way. I have had some good success with it and believe it to be an excellent technique in any stage of the problem solving process, whether I am dealing with professionals, layman, mechanics, or bozos.
Very helpful, well written and well-organized book. The $15 or so for the book is a great investment for your career or business. I am sure there are more comprehensive books that cost alot more, but this one fulfills it purpose nicely.