In my medical class they had a section on soft tissue damage and burns. They came up with a clever way, based off percentages, to divide the body up in regions. The percentages were based off of groupings of multiples of 9. For example, the front torso is approximately 18% of the surface area of the human body. One of the arms and hand would be 9%.
This method is used to quickly determine how much someone's body may hand been damaged due to burns. A gruesome topic, yes, but one I find useful in RPG hit locations.
You can think of it not as percentages but rather "slots". Each arm has 1 slot, while the front and back torso each get 2 slots. The head gets 1 slot while each leg gets 2 slots. Finally the groin region would get 1 slot. Add up all the slots and you get 12.
For Open Adventure (https://plus.google.com/communities/112108732479175981421
) I would use either 1d12 or compensate with 2d6 to use this system.
1-2: Left Leg / Foot
3-4: Right Leg / Foot
6-7: Torso (Front)
8-9: Torso (Back)
10: Left Arm
11: Right Arm
If you roll a side of a torso that is not applicable (for example, the back of the torso from a frontal attack) simply treat it as the side of the torso that works!