I love promoting skepticism, especially among all you young whippersnappers out there (as long as you GET OFF MY LAWN!). Teen Skepchick is a good one, for example.
Podblack Cat sent another suggestion along: Young Australian Skeptics. It shouldn't be too hard to figure out what that's all about. I like seeing what younger folks think about skepticism, and how they think about it. When I was a teenager I believed in all sorts of nonsense, and it took me a long time to grow out of it. These kids are already a decade ahead of me. Where will they be in another decade?