Even more good stuff
If I haven't convinced you yet to go to the bookstore right now, and get a copy of this book, here are few more highlights...
Placement conventions. In applying the principle of not reworking conventions that people are already familiar with, Steve gives examples of types of page content and where they should live on the page. He does a great job of describing various types of page elements such as, site ID, main sections, utilities, and local navigation. He compares the placement of page elements on a web page to the placement of street signs on roads. If someone were to decide to place street signs 10 feet before the corner (which might make sense because you would see the name of the street before you had to turn) the result would be, people wouldn't look for them there, and would miss them. In the same way keeping the location of navigation and other page elements generally consistent with other similar sites will make the site easier to use.
Page names. What you call your pages, and where you place their names is another important aspect to not making site visitors think too much about how to use it. Clear labeling and logical dominant placement of titles is a simple principle, but often overlooked.
"The Trunk Test." This is a great concept for testing the navigation and labeling of a sub page in the site. He gets us to imagine that we were blindfolded, put in the trunk of a car, driven around for a while and dumped off on a page somewhere in the depths of the site. Would you know where you are? Would you know what town, or block you were on? This test is extremely important because people are going to spend most of their time on sub pages, or detail pages (this is often where the real content is!). Also, because search engines can easily drop people off at a sub page of your site, providing overall orientation and sense of place in the site is critical, especially on low level detail pages.
A short list of other books we recommend
While Don't Make Me Think is an excellent resource, there are a few other books we would recommend:
Designing Web Usability, by Jacob Nielsen is a popular resource and he also does a great job of getting beyond the surface of the look of a website and getting into its usability.
The guru of information design is Edward R. Tufte. His books The Visual Display of Quantitative Information, Visual Explanations: Images and Quantities, Evidence and Narrative, and Envisioning Information are not written for the web but are deep and thoughtful tomes on the underlying principles of information display and design.
Information Architecture, by Louis Rosenfeld & Peter Morville is also a great book on how to think through the issues of categorization and organization of information.
Finally, Information Architects, by Richard Saul Wurman is another worthy book on the application of information design principles to interactive media.
