Do you know Google Maps? It's the browser based, lightweight version of Google Earth (I hope you do know what that is).
We are using it along with Google Maps API, in one of the subjects I participate in the University. The course is a workshop where groups of four students develop a J2EE based system on a proposed scenario.
This semester the proposed scenario is to develop a sort of treasure hunt game that integrates with Google Maps, using the Google Maps API. Like a web based where in the world is carmen sandiego version.
When I noticed that is also possible to achieve some level of animation, the options grow even larger. For instance do you remember the UFO game, by Microprose, which has a world map view, where you can see you XCOM bases in the world. It could be possible to do something similar to that (of course, without the missions), hunting in this case aliens across the world, starting from UFO sightseeings.
After I googled for Google Maps Games, I realized I'm not among the first ones to realize this, since there are already tons of implementations over it. Is it me, or game programming is made easier every day?
Besides game programming, there are other very interesting applications made on top of GM API, some of them which are reviewed here.