I have always wanted one of these spiked backpacks. They’re the best way to make hauling heavy books around awesome. And more prehistoric.
Aww, these backpacks by Chooze are so cute! And you can get coordinating lunch boxes to go with them — double aww!
If a messenger bag is your thing, or you're really into riding a bike, a Timbuk2 bag is a great choice. They rest at your hip for easy access, and also feature a counterweight strap to stay in place when you're cruising.
There’s always the one-shoulder option for the teen who you know isn’t going to use both straps, even if they’re provided. They might prefer something like this cool, rope-strapped sling bag.
What I remember most about toting my books around campus was how insanely heavy they were. If you've got a bookish backpacker on your hands, consider looking for something like this that features particularly padded shoulder straps to help avoid the digging-in pain that academic backpack users know all too well.