The Basics
Sex and Masturbation Resources

Avert: Young People's Section - http://www.avert.org/yngindx.htm
Puberty, safe sex, masturbation, STDs, and AIDS, as well as issues related to homosexuality in teens of both sexes.

Teenwire - http://www.teenwire.com/
Site with various relationship and sexuality information.

Sex, Etc. - http://www.sexetc.org/
Advice for teens about sexuality, masturbation, contraception, drugs, smoking, and related topics

Scarleteen - http://www.scarleteen.com/
Advice, help and information about teen sexuality and masturbation. Special sections for teen gals and guys.

It's Your Sex Life - http://www.mtv.com/thinkmtv/sexual_health/
Safe sex and protecting themselves from disease and unwanted pregnancy.

I Wanna Know - http://www.iwannaknow.org/
Sexual health and STD prevention information for teens, including chat, education, games, and other resources.

Coalition for Positive Sexuality - http://www.positive.org/
Intended to give teens the information they need to take care of themselves and affirm their decisions about sex and reproductive control.

Puberty 101 - http://www.puberty101.com/
Uses questions asked by teens to provide information about the various aspects of puberty.

The InSite - http://www.theinsite.org/
Information about reproduction, birth control options, sexually transmitted diseases, masturbation, and relationships. Also includes letters from other teens.