Ever heard of a massively multi-user persistent environment? Chances are you probably will later on this year. Gaming company There is building a virtual model of the Earth, in scale with the real one! There is making it for the US Army to train for future conflicts all over the globe. It will be contructed from a real-world terrain database and eventually include characters and models with AI that can react to different events like they do in the real world.
If you want to read more, check out the BBC article.