Casino Gambling Central - Free Sweepstakes & Lottos

CBS SportsLine: Visa Office Pool Challenge
ESPN.com: Pigskin Pick'em - predict who will win each game throughout the NFL season.
Internet Football Pool - compete against players from around the world to win weekly prizes.
NFL Championship Challenge - win prizes by making football picks against the Las Vegas odds.
Office Football Pool.com - participate in or create custom NFL and college football pools.
Play the Pool - offers a free weekly pool.
Probability Football - contest based on choosing the probability that a team will win.
SportsRocket.com - Football Pick'em