FlyAcesHigh WW2 Combat Game
Interactive Game Get a free 2 week trial of this online WWII combat game. Engage in air, land, or sea combat. For squadrons with other live players. Create your own missions or play historical scenarios. Online gaming action 24 hours a day.

Games for free or for cash prizes at WorldWinner
This site has a mix of unique games that can be played for free, or if you set up an account, you can play games for prizes. They specialize in "online skill based games for cash and merchandise prizes, offering free and real money sports, card, strategy, arcade and word games."