Here are some cool websites designed specifically for Christian teenagers:
Christianity Today has a website for teens with advice, true stories, music, college guides, and some other fun stuff.
Christian Students is another cool website that you should check out. This site covers many of the hot topics such as entertainment, sex/dating, school, life issues, and more...
christianteens.net - This site contains chat rooms, music, teen message boards, connection with other youth groups, christian e-greetings, and a bunch of other stuff...
If you find some other cool sites for Christian teenagers feel free to post the links in the comment section.