These three books are specifically about motivating software developers:

DeMarco, Tom, and Timothy Lister. Peopleware: Productive Projects and Teams. New York: Dorset House, 1987. DeMarco and Lister present many guidelines both for what to do and what not to do in motivating software teams.

Weinberg, Gerald M. Becoming a Technical Leader. New York: Dorset House, 1982. Part 3 of this book is about obstacles to motivation and learning how to motivate others.

Weinberg, Gerald M. The Psychology of Computer Programming. New York: Van Nostrand Reinhold, 1971. Chapter 10 of this classic book deals with motivation specifically, and the rest of the book provides insight into the programming mind-set, which will be useful to anyone who wants to understand what makes developers tick.

These two books provide insight into how Microsoft motivates its developers:

Cusumano, Michael, and Richard Selby. Microsoft Secrets: How the World's Most Powerful Software Company Creates Technology, Shapes Markets, and Manages People. New York: Free Press, 1995.

Zachary, Pascal. Showstopper! The Breakneck Race to Create Windows NT and the Next Generation at Microsoft. New York: Free Press, 1994.

These three books and articles are about motivation in general:

Herzberg, Frederick. "One More Time: How Do You Motivate Employees?" Harvard Business Review, September–October 1987, 109–120. This enlightening article discusses motivating employees through focusing on job enrichment and "growth motivators" rather than on hygiene motivators. The original article was published in 1968 and was republished in 1987 with some new comments by the author. By the time it was republished, the article had sold more than a million reprints, making it the most popular article in the history of the Harvard Business Review. I rarely laugh out loud while reading professional publications, but I did while reading this one. It is probably one of the most humorous articles ever published by the Harvard Business Review.

Peters, Tomas J., and Robert H. Waterman, Jr. In Search of Excellence. New York: Warner Books, 1982. This book is not about software, but snippets about how to motivate technical and nontechnical workers are threaded throughout the book.

Hackman, J. Richard, and Greg R. Oldham. Work Redesign. Reading, Mass.: Addison-Wesley, 1980. This book explores work-itself related motivations and proposes a framework for redesigning work to improve motivation, productivity, and quality. It contains valuable information, and the authors have earnestly attempted to make the book easy to read, but it's a heavy-duty psychology book. As someone without a psychology background, I found it to be slow going.