Substance Abuse
National Institute on Drug Abuse
National Institute on Alcohol Abuse and Alcoholism
National Substance Abuse Web Index 
QuitNet, Encouragement to quit smoking
Treatment 4 Addiction (Online recovery and resource directory)

Suicide
National Coalition of Homicide Survivors
Suicide and Sudden Loss: Crisis Management in the Schools, including counseling tips
Youth Suicide Prevention Programs: A Resource Guide

Family Related
Family Matters, from My Virtual Reference Desk
National Institute of Child Health and Human Development
American Academy of Child and Adolescent Psychiatry
Focus on the Family
Fireproof My Marriage

Relationships
PAIRS (Practical Application of Intimate Relationship Skills)

Abortion
Rachel's Vineyard

Addiction and Pure Living
Setting Captives Free