Recently the field of computer-human interaction has exploded with new ideas, technologies, and issues. In response to these many developments, Apple presents this beautiful, full-color book that not only describes the interface guidelines for Macintosh computers, but also examines the theory behind the famous Macintosh "look and feel" and the process of designing and testing an interface.
A lot of the info you'll find here is somewhat dated, since it's specific to the Mac GUI as it existed at the time of publication, but the sections dealing with the concepts and principles of interface design are still the best I've ever seen, and are relevant regardless of platform. The web would be a far friendlier place to visit if those responsible for designing sites spent a few hours with this book.
If you’re an interface designer, a must read. Really helps you understand the intent of the original Mac GUI, and how so many of today’s patterns are rooted in these designs.