Sparkpeople
Free diet service that allows you to track your calories and exercise. Provides meal plans and grocery lists. Also allows chat rooms with other dieters.
Tricare Resources
Tricare has online weight management program that is self-paced available on the Healthy Living page. Also offers information, tools, calculators, printable resources and phone based classes on other health topics such as self-care and tobacco cessation. Try it today.
TeensHealth
A site just for teens that covers topics from doctors visits (including gynecology) to how to write papers for English class.