The Betabrand Ultra Slim Laptop bag is basically a MacBook Pro sleeve that you can wear under your jacket or hoodie.
This is perfect if you need to take your MacBook Pro around town without worrying about advertising that you are carrying a laptop and other gear with you.
The Betabrand Under-The-Jack-Pack 2.0 is only 1.5-inch thick and it is designed to be work under a jacket or loose fitting clothing so you can conceal your gear. if you decide to wear it on the outside, it is coated in special material that is super-reflective so that you have an extra layer of visibility when walking or biking at night. This bag works both ways, staying covert when you need that and showing off when you don't need to keep it a secret.
Betabrand sells this in a 13-inch and a 15-inch version and there is enough room for a few other items in your bag while still being small enough to carry under a jacket.