Taking a little more than a passing interest in football strategy and analysis, I have stumbled upon the following resources:
Football Outsiders: Football's attempt at sabermetric-style analysis. The differences in variables between baseball and football pose a challenge to this approach, but FO offers an admirable effort to bridge the gap.
American Football Association: An organization devoted to the promotion of semi-pro and minor league football.
Gridiron Strategies: A site devoted to football coaching strategies.
Reference as you please.