I was asked recently about the FlexCarry case from Motion Computing that is designed to fit the C5 and F5 Tablet PCs. The case comes in white (more of a "bone" if you asked my wife about the color) and includes a black shoulder strap that you can also attach.
The case doesn't add much weight or bulk to the unit and provides extra protection for the display because if the tablet were to be dropped screen down then the case would prevent it from hitting directly on the floor or whatever you dropped it on.
The case does need to be partially removed in order to access the battery which is inconvenient but I don't see how a better case could be designed for easy battery access.
Here are some pics: