A recent report by the Nielsen Norman Group details the browsing trends of teenagers and the results are very interesting from a web design perspective. Apparently teenagers are a fickle lot, and like sites with big writing and lots of pictures and a stylish layout and more then that, they are more likely to stick around on interactive sites.
Sites that show respect for teenagers and cover the issues important to them are more likely to gather that audience, and considering this age group are the future adults, and already account for a significant percentage of the web using public, they are an important audience to target. Read more here.