The Lull-A-Baby Sleep Plan: The Soothing, Superfast Way to Help Your New Baby Sleep Through the Night...and Prevent Sleep Problems Before They Develop by Cathryn Tobin, M.D.: This book -- published last year -- features a 7-day plan that can be used to take advantage of a sleep learning window of opportunity that, according to the author, occurs at around six to eight weeks. If you've missed that window of opportunity, you can still use the book to re-train older babies and toddlers.
Sleep (Johnson's Everyday Babycare): This book provides a concise overview of sleep-related issues. This is a great place to start if you're bleary-eyed and having a hard time concentrating on anything longer than a grocery list.
Sleep: The Brazelton Way by T. Barry Brazelton: A brief introduction to the world of babies and sleep. Again, this book would be a good place to start if you're too exhausted to tackle a "big sleep book" right now.
American Academy of Pediatrics Guide to Your Child's Sleep: Birth Through Adolescence: A medically-oriented guide to children and sleep. Because the book covers a huge age range (birth to adolesence), only a small part of the book focuses on babies. Still, what is there is very useful as long as you aren't put off by the sometimes conservative tone. An excellent resource guide for the more medical-oriented sleep questions.
Sleeping Like a Baby: A Sensitive and Sensible Approach to Solving Your Child's Sleep Problems by Avi Sadeh: Avi Sadeh looks at the science behind infant sleep. He does a good job of differentiating between sleep problems and sleep disorders and provides a lot of reassuring words and helpful advice (via case studies) to parents who are wondering if they'll ever sleep again.