Best parenting book. Period.
How to Talk So Kids Will Listen & Listen So Kids Will Talk
How to discipline kids:
Parenting With Love And Logic
Since love comes first before logic, I'd recommend this book. It's a best seller for relationship between couples but has a kids version as well:
The 5 Love Languages: The Secret to Love that Lasts
Kids's whole brain development, not only the emotional intelligence:
The Whole-Brain Child: 12 Revolutionary Strategies to Nurture Your Child's Developing Mind
For strong-willed kids:
Setting Limits with Your Strong-Willed Child
Raising Your Spirited Child, Third Edition: A Guide for Parents Whose Child Is More Intense, Sensitive, Perceptive, Persistent, and Energetic
For gifted children:
The Talent Code: Greatness Isn't Born. It's Grown. Here's How.
For Math skills: (Third Grade or Above)
Secrets of Mental Math: The Mathemagician's Guide to Lightning Calculation and Amazing Math Tricks
For school age kids:
How We Learn: The Surprising Truth About When, Where, and Why It Happens
Best book for kids with siblings. Period.
Siblings Without Rivalry: How to Help Your Children Live Together So You Can Live Too
The Triple Package: How Three Unlikely Traits Explain the Rise and Fall of Cultural Groups in America