At Zappos, this Nike Heritage Eugene backpack is 50% off. You'd pay $10 more for an almost-identical one directly from Nike.
The 23-liter bag has a padded sleeve for laptops up to 15", a water-resistant coating, and a side pocket for a water bottle. Free shipping is included, too.
Buy Now at Zappos
Features 23-liter capacity Padded sleeve fits laptops up to 15" Water-resistant coating on woven polyester Front and side zippered pockets plus a water bottle pocket Padded shoulder straps and cushioned back panel Measures 18" high x 12" wide x 6" deep