Everything this book says is just common sense. When designing websites, it's easy to lose sight of the fact that people will actually be using your published work! How many times have you been to a site only to think "where's the search box" or when entering some details into your online bank account and then press the "enter key" it doesn't login, it goes off to a "apply for a new savings account". Very confusing. In these circumstances, your brain has to think about what has happened, leaving a negative impression in your mind. Not good if you're trying to sell something!
When it comes to the web, first impressions count. Take Amazons new redesign for 2008. Amazon gets quite a lot of coverage in the book as an example of good design, so it's interesting that they have gone away from their old design, that's been around for about a decade. I don't like the new look, because every time I use it I have to think whereas before it was intuitive. That's the whole point of "dont make me think". You should never have to think about how to use a web site. If you need to use your brain to do something simple, the designer has FAILED.
"Dont make me think" is a quick and easy read. It's quite small at 200 pages. It's often reduced on Amazon so keep an eye out for a bargain.
Highly recommended for all developers, even if you don't often do user interfaces. The advice can be applied to all interfaces and not just the web.