Where In the World Is Carmen Sandiego is still a geography gaming classic. This online geography game is run in blog format. Clues are posted on the website, and then players can post comments, tweets, or Facebook comments alluding to their guesses about where the villain is now hiding. Each clue is brief and lively, and it's a lot of fun. Best of all, the game is free!
GeoQuiz by Lizard Point This game is a quiz-show like game, and it allows players to select the regions they would like to be quizzed on. Players are then asked where various geographic regions are, and they then click on the region with the computer's mouse. This game is also available for free.
GeoNet is another fun and free online geography game. This game allows players to answer multiple-choice questions. However, that's not all, because there are actually many different mini games players can engage in on this site. Players choose whether to focus on the United States or the World. Once that decison is made, you can select the region and then the focus for the questions. The game features fun sound effects.
PlaceSpotting is a game that uses Google.maps to teach about geography. Players match the top picture with an area on Google.maps by zooming in and moving the view. This game is quite challenging but neat because you get to view satellite views of the different geographical regions.
Playfish's Geo Challenge is a game that teaches geographical awareness, familiarity with the flags of various nations and states, and fast thinking. The game is a lot of fun, but it's on Facebook. If you're not allowed or old enough to have a Facebook account, you might want to try using the game on your parent's account, with their permission, of course.
Free Poverty is both a geography challenge and a relief organization. Every time you get a correct answer, the organization donates 10 cups of water to a country in need of clean drinking water. That means that your efforts go to a good cause. I got sucked into this game for a few minutes before remembering that I have a job to do.