Here are some of the best places on the web to find effective, age-appropriate, medically accurate sex education programs.

Creating a Safe Space for GLBTQ Youth: A Toolkit

Curriculum from SIECUS

Resources from Healthy Teens Network

Lesson Plans from Advocates for Youth

Activities for Educators from Planned Parenthood Federation of America

Curriculum from Girls Inc.

The Program Archive on Sexuality Health & Adolescence (PASHA)

F.L.A.S.H. Family Life and Sexual Health link
Curriculum out of Washington State is a great free resource with downloadable lesson plans.

NEW for purchase:

Making Sense of Abstinence: Lessons for Comprehensive Sex Education (pdf)

The Librarian's Guide To Sex Education Resources link
Audiovisual, print, and Web-based materials for youth, parents, and youth-serving professionals.