In my department, we all use the Ogio Metro backpack. We love them so much that our IT group is starting to substitute these for the standard laptop briefcase whenever replacement computers are ordered.

The laptop compartment is tucked away at the back of the backpack, so removing the laptop for security screening is a breeze. It doesn't scream "I have a laptop" either, which is good for me!

http://www.ebags.com/ogio/metro/prod...?modelid=50968