Parents Magazine - advice by age (mostly geared to younger children). Health & safety issues, etc. http://www.Parents.com/
WebMD - Medical issues, discussed by age group. http://www.WebMD.com/
Substance Abuse and Mental Health Services Administration http://www.samhsa.gov
Bullying, Cyberbullying and School Violence Prevention http://www.stopbullyingnow.com
http://www.saferchild.org
http://www.wiredsafety.org
The Parent Institute - resources for parents on improving student success. http://www.parent-institute.com
NYU Child Study Center - latest research and resources on mental health/health issues for children and adolescents. http://www.aboutourkids.org
National Center for Learning Disabilities http://www.ld.org
Autism Society of America http://www.autism-society.org