Here are a few websites which I found provides quite useful information & advices on a wide range of topics.

Ask Dr. Sears
Covers topic on pregnancy, breastfeeding, sleep & discipline issues, kids nutrition, health/illness etc.

Pediatrics
Medical advices, experts’ Q&A, Information and advice on dealing with common parenting issues and problems, including nutrition, growth, development, sibling rivalry, potty training, managing behavior problems and temper tantrums etc.

Young Nutrition
nutrition advice, experts’ opinions & recipes