The Cloak Bag($50) is a camera bag that lets you take pictures whilst your camera is still inside.
The Cloak Bag is designed to keep the camera protected and out of site, yet you can quickly flip it open and shoot with the camera still inside. A strap replaces your actual camera strap, and then the case itself hooks onto it with Velcro and a screw in the tripod-mount. The bottom of the bag zips open and folds inside when you want to shoot. In this mode, it looks like any other shoulder bag.