[Ernestas]

The Non-Designer's Design Book: Design and Typographic Principles for the Visual Novice - Outlines the essentials of page layout, emphasizing the four concrete principles of design--proximity, alignment, repetition, and contrast

[blahblahblah]

I'll second that recommendation. It's such a quick read and yet so incredibly insightful. The same author also wrote a sequel to the book intended specifically for the web. I haven't read her web design book, but if it's anything like the original I'm sure it's a valuable addition to any web designer's library.

In addition, I'd recommend: "The Humane Interface: New Directions for Designing Interactive Systems" by Raskin

and

"User and Task Analysis for Interface Design" by Hackos and Redish