Google Earth: Street View Games
I never knew Google Earth had Streetview Games until I read about it on the HistoryTech Blog.
You might want to check out some of the games Glen shared:
Streetview Zombie Apocalypse
You select a location where you want to get dropped and using StreetView, have to avoid, well . . . zombies who want to eat your brains.
Pretty much what it sounds like. Questions that you can solve using the clues contained in the StreetView.
Real World Racer
Choose a route (a pre-created one or one that you ask your kids to create) and then race your car against the computer using keyboard controls. Pretty simple but you could have kids create a track around a battlefield or through different regions.