I never really have that much off time because of football but when I do get time off I really enjoy wrestling. Wrestling has been really helpful with improving my footwork and conditioning. I think wrestling really did help me out with football, a lot.
Can you imagine having to wrestle a 6'9" giant in high school? I never wrestled and have heard on more than one occasion that a low center of gravity is advantageous, but I gotta believe that at least a small part of you, even if only for a moment, has to be like "son of a ..." when you see someone his size step onto the mat opposite you.