This book was recommended to me by a friend who designs rugs and is an architect as well. I bought it for my own use as an interior designer and to help me with paint colors and overall color scheming. It is a great device for getting a feel from your client of what colors he/she prefers. Its a wonderful gift for people in the trade.
This book and its companion, "Color Image Scale," are excellent sources of palette ideas for web work. (If you buy one, buy both.) As an amateur designer, I found their treatment of the emotional impact of color groupings to be enlightening and thought inspiring. On the down side, they dont provide CMYK or RGB values--a minor inconvenience.
This is a fantastic resource for anyone designing in colour. I do mostly online design and use this book every day. It is a specialised colour combination scale based on research done by the author. Pick a base colour and see its combinations, what they mean to most people and where they are typically used. Awesome stuff!