Can you help me find a backpack?

I've been using a large tote bag, but i have so much stuff to carry that my back hurts after only a week of school, so i'm switching to a backpack. The problem is that most backpacks look kidish and utilitarian, and i like to think i have a more refined, sophisticated style. One that doesn't include backpacks. Does anyone know where i could find a cute, cly, functional backpack? Links are appreciated.