Two books recently recommended to me by my artist friends, Richard Schmid and Nancy Guzik:

The Artist's Guide to Selecting Colors

This is an excellent book about popular artists' paints on the market today: a guide to the selection of a suitable palette in all mediums - watercolors, oil paints, acrylics, gouache or alkyds. It will enable you to identify the good, the indifferent and the bad. It also outlines the characteristics and temperaments of each color and lists the suitable as well as the unsuitable pigments that you will come across.

Atlas of the Human Anatomy for the Artist

In an effort to improve my figure painting skills, I've decided to start with the practice of drawing and studying the human anatomy. This book - recommended by Nancy - is designed to aid the artist in the execution of correct proportional drawing of the human body, and also gives an in-depth look at bones, muscles, and basic human-body structure.