"How to Make Your Money Last: The Indispensable Retirement Guide" by Jane Bryant Quinn
I love this book! I think that everyone who's close to retirement, or in retirement, will benefit from reading this book. You can read it all the way through, or just go to the specific areas you have questions about at the moment. Ms. Quinn's years of researching personal finance are summarized in this book, which boils complex issues down to what you need to know.