There are innumerable books on design and related areas. As some of my background is in human-computer interaction, I can refer you to some popular work on designing computer interfaces. Many of the techniques and concepts generalize well to other problems.

Eberts, R.E. (1994). User Interface Design, Prentice Hall.

Laurel, B. (1990) The art of human-computer interface design. Addison-Wesley.

Lewis, C., Rieman, J. (1993) Task-centered user interface design --- A practical introduction. Shareware book, available by anonymous ftp or with a simple front-end on the World-Wide Web.

Mayhew, D. (1992) Principles and guidelines in software user interface design. Prentice Hall.

Mullet, K., and Sano, D. (1994). Designing Visual Interfaces: Communication Oriented Techniques. Prentice Hall.

Norman, D. (1988) The Design of Everyday Things (formerly The Psychology of Everyday Things). Basic Books.
Norman, D. (1992) Turn Signals Are the Facial Expressions of Automobiles. Addison-Wesley.
Norman, D. A. (1993). Things that Make Us Smart: Defending Human Attributes in the Age of the Machine. Addison-Wesley.
Norman, D. A. (1998). The Invisible Computer: Why Good Products Can Fail, the Personal Computer Is So Complex, and Information Appliances Are the Solution. Cambridge MA, MIT Press

Olsen, D. (1998). Developing User Interfaces. Morgan Kaufmann.

Preece, J., Rogers, Y., Sharp, H., Benyon, D., Holland, S., Carey, T. (1994). Human-computer interaction. Addison-Wesley.

Preece, J., Rogers, Y., Sharp, H. (2002). Interaction Design. John Wiley.

Raskin, J. (2000). The Humane Interface. Addison-Wesley.

Shneiderman, B. (1998) Designing the user interface. Third edition. Addison-Wesley.

Tognazzini, B. (1992) Tog on interface. Reading, MA. Addison-Wesley. Tognazzini, B. (1996) Tog on software design. Reading, MA. Addison-Wesley.

Tufte, E. (1983). The Visual Display of Quantitative Information. Graphics Press.
Tufte, E. (1990). Envisioning Information. Graphics Press.
Tufte, E. (1997). Visual Explanations. Graphics Press.

Winograd, T., Bennett, J., De Young, L., and Hartfield B., eds. (1996) Bringing Design to Software. Addison-Wesley.