Here's an innovative case idea: Do away with the case for your laptop altogether and just attach Handle-It, a carrying handle that connects to the 13" MacBook's existing holes in the back. The handle's not going to do much to protect your beloved bauble, but with such an attachment you can be sure your yoke is easy and your burden is light. There are other benefits to this design, too.
When you're ready to get to work after reaching your destination, fold the handle underneath your MacBook and the aircraft aluminum metal serves as a passive heatsink, enhancing airflow underneath. Made of Italian cobblestone leather, it's available for $49.99 in black or white to match your 13" MacBook. Too bad all laptops don't have those special holes in the back to which you can attach such a thing.