Chess.com - http://www.chess.com/ The #1 place to play free online chess and learn chess rules, openings, & strategies. You can also find chess games, explore downloads, & review chess sets.
The Red Button Game - http://www.coolbuddy.com/games/The_Red_Button/The_Red_Button.htm Shoot the bad guys to change history for the better.
You Don't Know Jack - http://www.youdontknowjack.com/ Quite a twist on a trivia game. This one can sometimes make fun of you. Odd questions make answering things you already know a bit more difficult. I've been playing for over 10 years.