This would be an excellent candidate for a sticky post in one of the general reference forums.
I would add some clarification to one or two, namely:
CHP is typically used in Virginia, since it's the specific name of our permit.
You sometimes see RTKBA, Right to Keep and Bear Arms
I have seen LTC mean License to Carry, not necessarily Conceal. Many states it means carry, but manner (open / concealed) is optional.
I think some states have a LTCF License to Carry Firearms.
The IWB OWB are usually meaning Inside and Outside, I is usually for concealed, O is usually for open carry.
GFSZA is the Act (federal law) we all love to hate.
BUG: Back Up Gun (among others)
Some use IMHO for In My Humble Opinion
VCDL Virginia Citizens Defense League, and a number of other fine organizations could be included. You could probably have a separate section for just these, there are so many, especially when you start to consider other states: WVCDL, PAFOA, etc, etc, etc.