Book: Universal Principles of Design (Lidwell, Holden, Butler)
If you are interested in learning design theory, I recommend Universal Principles of Design by William Lidwell, Kritina Holden, and Jill Butler (2003, Rockport). This book includes 101 design topics in perception, learning, usability, appeal, and application. Topic discussions include theory from psychology, marketing, computer science, and graphic design.
Not all examples are computer systems; but the theory is explained well which makes it easy to reapply what you learn when designing a user interface design. The book format makes it both easy and interesting to read (one topic per page), is great as a reference guide, and has lots of pretty pictures.
Another recommendation I’ve made is for Designing Interfaces by Jenifer Tidwell (2005, OReilly). Designing Interfaces is focused on detailed examples and specific problems in computer software. Universal Principles of Design covers much more design theory but with examples across domains and media. Both are excellent books for those interested in user interface design and usability.

Universal Principles of Design is a wonderful book. I was elated when I added it to my library years ago.
If there is one thing that is apparent, it is clearly that the principles will become paradoxical without an audience. One key component missing from the wonderful book is most certainly highlighting the guiding element to all aspects of design — one’s audience.
I would be as bold as to suggest that KDE’s current dilemma, GNOME’s decadence discussion, and those issues that plague Ubuntu, are solely rooted in the avoidance of a clearly stated audience.
As per Aesop:
A Miller and his son were driving their Ass to a neighboring fair to sell him. They had not gone far when they met with a troop of women collected round a well, talking and laughing. “Look there,” cried one of them, “did you ever see such fellows, to be trudging along the road on foot when they might ride?’ The old man hearing this, quickly made his son mount the Ass, and continued to walk along merrily by his side.
Presently they came up to a group of old men in earnest debate. “There,” said one of them, “it proves what I was a-saying. What respect is shown to old age in these days? Do you see that idle lad riding while his old father has to walk? Get down, you young scapegrace, and let the old man rest his weary limbs.” Upon this the old man made his son dismount, and got up himself. In this manner they had not proceeded far when they met a company of women and children: “Why, you lazy old fellow,” cried several tongues at once, “how can you ride upon the beast, while that poor little lad there can hardly keep pace by the side of you?’ The good-natured Miller immediately took up his son behind him.
Did you ever see such fellows, to be trudging along the road on foot when they might ride ?
They had now almost reached the town. “Pray, honest friend,” said a citizen, “is that Ass your own?’ “Yes,” replied the old man. “O, one would not have thought so,” said the other, “by the way you load him. Why, you two fellows are better able to carry the poor beast than he you.” “Anything to please you,” said the old man; “we can but try.” So, alighting with his son, they tied the legs of the Ass together and with the help of a pole endeavored to carry him on their shoulders over a bridge near the entrance to the town. This entertaining sight brought the people in crowds to laugh at it, till the Ass, not liking the noise nor the strange handling that he was subject to, broke the cords that bound him and, tumbling off the pole, fell into the river.
Upon this, the old man, vexed and ashamed, made the best of his way home again, convinced that by endeavoring to please everybody he had pleased nobody, and lost his donkey in the bargain.
(text of Aesop’s original taken from http://living.oneindia.in/kids/short-stories/2008/aesops-fables-please-everybody-200608.html)
I taught a class on Graphical Interface Design last Fall and purchased Tidwell’s Design Patterns book to use as a supplement to my lectures. I’m surprised you rate it so highly.
In my opinion it contains very little worthwhile content. Most of the text is an uninspiring list of widgets available to GUI developers. What wasn’t obvious was usually impractical or useless. The really important theme of what strategies to use when was barely addressed.
The introductory chapters of the book were mildly useful. But overall, I was horribly disappointed.
Is the Lidwell book better in that regard?
atmopawn: I rate Tidwell’s book highly for developers who are new and interested in user interface design — not for experienced designers. It is pretty primary in that regard. Universal Principles of Design is much more diverse in discipline, so even if you are a classically trained graphic designer, there are probably some topics that are new for you to learn, such as those which come from market research and psychology. Again, this is a great book for developers who are new and interested in design theory; but perhaps too primary for seasoned designers who will pick up the new information quickly and move on. I’ve outgrown the book in terms of knowledge, but still reference it every once in a while when I forget exact details. The one-topic-per-page format makes it easy to flip through and browse for fun.
Seele, Please I can have your babies?