I was reading Kim Shay's lament about the overall lack of modesty in society, and I was reminded of Carla Rolfe's post from last year entitled "Dressing Girls." In it, she uses the phrase "Welcome to SkankWorld." My wife and I still talk about that one when we are together at any store that carries clothes.
Modesty is a difficult thing, to be sure. Because it is open to interpretation, it feels subjective. There is also the possibility that people will fail to recognize that the Bible has relevance here, even without a verse that reads "Don't let your skirt come up past your knees," etc.
The Way of the Master radio podcast had an episode recently where they gave a modesty quiz. The quiz originated from the Family Life folks (who are actually out of Arkansas), and their stuff is good. It sounds like something that might be helpful, or at least encouraging, for those who are searching for ways to instill modesty in their children.