Windows only: Ever get embarrassed by how little you know about the world outside your immediate area? Enigio, a free Windows quiz app, brings you up to speed with quizzes that fill in all the map gaps.
Fire up Enigio, and you'll get to set up your own quizzes. Set up your questions by the percentage of the world covered, sorting by population, area or density, choose text input or multiple choice, or limit your quiz to a particular area of the world. Soon enough, you'll be a little bit smarter about where things are on a map.
Enigio is a free download for Windows systems only.