I can't go to bed tonight without pointing you in the direction of these two posts on Tama's blog. Read this one first then this. They're posts about beauty and self image and how images are distorted by the media and marketeers. I can't paraphrase them or summarise them in any way that does them justice. Just go and read them.
Oh, and if you know a young girl.... Hug her and tell her she's beautiful.