by Robin Williams
I have no idea why I picked this up well over a year ago, but I'm glad I finally found the time (read: about an hour) to read it. It gives an overview of basic design principles, easily remembered using the mnemonic C.R.A.P. (for Contrast, Repetition, Alignment, and Proximity). What I found most interesting, however, were the chapters on typography.
I'm consistently amazed by the designers that I work with who are easibly able to identify a font after looking a few letters. They can also change a single font on a page and really bring the page alive. Until I read this book, I had no idea how they did it. In fact, I still don't, although I have a better idea about the types of things to look for.
In any case, this book is useful if you want to be able to really tie your room together, but have the design sensibilities of a large boulder. I know I will be referring back to this book a few times as I redesign this site...