Jeremy,
A good way to test would be by doing a deadlift. If you finish the lift, and the bar is near your knees, then you have long arms or a very short torso. If you finish and the bar is at or above your crotch (like me) then you either have short arms or a very long torso.
Also when floor pressing, if the bar stops very far above your chest (5 inches or more) then you have long arms or a little chest. If however the bar is close to your chest, or touches your chest at the bottom (once again, like me) then you either have a huge chest or short arms.
You could also just go to a tailor and get measured for a suit. Ask him how your arms compare to average.
Like height and skin color, there is nothing you can do about it, so it is probably not worth getting real excited about it. If your arms are shorter, you are better suited for benching, and if longer you are better suited for deadlifting, throwing events, and pretty much any and all athletic endeavors.
B.