I tried the original GeoMaster app from French mobile developer VirtuaMobile a long time ago, but the HD version is well-suited to the bigger iPad screen. GeoMaster Plus HD is a geography quizzing game. It is simple enough, flashing text on the screen and asking you to tap the appropriate location. You battle against the clock but only to beat your times. This is a basic learning tool, and is fun yet relaxed, lacking really flashy or annoying elements. As such, it is perfect for kids learning geography. You can choose from states, countries, capitals and French departments, and players need only tap the appropriate spots on the screen to register answers.
GeoMaster Plus HD adds a few things for the iPad. The larger screen makes it somewhat easier to tap the maps. Still, you can pinch to zoom and swipe to pan around if you can't hit Rhode Island with your giant fingers. The graphics are crisp and attractive, and the app really nails the chalkboard look. The drawstring on the pull-down map (which accesses the Atlas) even interacts as you tilt the iPad. The Atlas is a basic factoid lookup tool for the geography used in the game. It isn't that detailed nor is it as fun to browse as the game is to play. There are much better atlas apps, so consider this a somewhat weak freebie.
Still, GeoMaster Plus HD is a fun, accessible and useful educational game for learning geography. Even at full price I can recall paying much more for flash cards which weren't nearly this enjoyable. Pick it up if you have a friend or relative who needs to learn some basic geography fast.