This isn't exactly a Linux mobile comment, but is worth sharing anyways. Recently I picked up the Wenger Coral notebook bag and it is quite nice. It is a double gusset computer case and has plenty of room for pretty much everything and anything! It can handle most 15.0/15.4-inch widescreen notebooks, easy access front pocket, expanding business files, business organizer, reinforced ergonomic handles, tear resistant shoulder strap, and limited lifetime warranty.
It's certainly not a cheap bag, but the Wenger Coral has excellent padding, storage compartments, etc... Check it out at Wenger North America, and below are a few shots of the empty bag. I am definitely enjoying this notebook case so far.