The Dynamic Characters concept art fundamentals book from 3DTotal.
"This book will talk about the basics of the creative process, the initial flow of ideas that you will transfer to the canvas, through which you will understand the design process itself.
Before we begin, I'd like to point out that the knowledge in this book can also be used in personal work, my focus and experience as a commercial artist will be turned in that direction. Now let's get to work!"
A "mast-heave" book for concept artists. It describes useful hints, tips on working with the concept: silhouettes, poses, searching for ideas.