I'm reading Understanding Wood Finishing : How to Select and Apply the Right Finish by Bob Flexner. I got it out of the library.
I've finished and refinished several pieces of furniture in my time, with varying degrees of success. I gleaned what I know about it from various TV shows, reading the directions on boxes and cans, and trial-and-error. This book completely obliterates that, with a great combination of physics, chemistry, and practical know-how. It describes the different kinds of finishes and how most of the stuff that manufacturers say about their stuff is bullshit, and that both simple things are good and the new stuff is not as much different from the old stuff as people would have you believe. Also, most wood finishing products are only a few hundred years old anyway, so it's again pretty similar. This is the only book I've read about wood finishing that manages to make it not seem like some mystical art, and just a simple application of principles.
If you've ever put a coat of Minwax on a piece of wood, or wondered what wax really does, or the difference between shellac, lacquer, and varnish, then this book is for you. It's so good I want to go back and fix the furniture I've previously finished, and now know how to get it just the way I'd like. It also makes me want to refinish other things. Good stuff.
Yes, I'm a geek who reads books about finishing wood. You'd think that'd be way down on my list (behind computers, music, cooking, gardening, landscaping, and home repair), but there you go.