http://www.tombihn.com/backpacks/TB0104.html
Expensive, but will last forever, is extremely comfortable, carries a lifetime warranty and if you're willing to spend for the accessories the bag is very flexible for different uses. I used mine for carrying (2) laptops, as a carry on, camera gear, and grocery shopping.
The only reason I stop using it for biking is because the bag can fit so much that it started to affect my center of gravity too much. I use to load it up with close to 15-20 pounds consistently.