The Acorn Principle: Know Yourself, Grow Yourself by Jim Cathcart Cathcart provides an amazing amount of information in this small book. Each chapter describes a different concept in the world of personal growth - each provides a starting place for more exploration.
The Definitive Book of Body Language by Allan and Barbara Pease This book is fun to read and very informative. It shows you how to pick up non-verbal clues from people, but also provides tips to help you communicate more powerfully.
You Just Don't Understand: Women and Men in Conversation by Deborah Tannen Tannen is a Professor of Linguistics and this easy read provides interesting information on the differences between how men and women talk and communicate.
Boundaries: Where You End and I Begin by Anne Katherine This comprehensive book defines boundaries and provides help in learning to define, establish and honor both your boundaries and those of others.
The Pathway: Follow the Road to Health and Happiness by Laurel Mellin This book changed my life by teaching me a way to identify, understand and "defuse" many of the negative emotions and impulses in my life. I highly recommend it to anyone who is battling habits such as overeating, smoking, drinking, etc.
How to Be An Adult by David Richo This little book blew me away! If you have ever struggled with establishing firm boundaries, standing up for yourself, or dealing with guilt, fear or relationships check out this quick read. Richo provides clear and concise information including suggestions for dealing with your fears and insecurities.
Getting Things Done: The Art of Stress Free Productivity by David Allen Using Allen's systems will help you organize your work and life, helping you stop forgetting things and eliminating those wide-eyed "oh-no's" in the middle of the night.
Allen also has a website where you can sign up for an excellent and informative newsletter.