For a Third Person game, how would I go about making the character's arm follow the camera? So I'm making a third person game, and I want to have the right hand follow the camera when aiming. How could I make this happen? Any suggestions are appreciated, thanks. 

Edit: Okay, I'll be more specific. I want the whole arm (the hand was a bad choice of words, I guess) to follow the camera in a way similar to that of most third person games that are out there now. (For example, Just Cause 2.) I tried the "Child Of" constraint, and it both made the hand very small and didn't change the movement of the hand whatsoever. There is an animation playing as this happens.
It really depends on how you are controlling your character and camera; there are many different methods (ie. camera actuator, edit object actuator -> mode: track to)

The way I would go about setting up controls like Just Cause 2 (shooting) is to add an empty for the location of the camera behind the character, and another empty (or object) for a reciticle and when holding down an "aiming" button move the camera to the location of the empty and "track to" the reciticle with both the camera and the arm/gun. And make the mouse control the reciticle.