An incredibly detailed reconstruction of Middle Earth is being made in Outerra, a 3D terrain program designed to model entire worlds.
"The scale model is called the Middle-Earth Project, and it is so epic in scope that you can see the Eye of Sauron from space, yet so finely detailed that you could zoom from space right into Bilbo's Hobbit hole. It's all accomplished with Outerra, a middleware graphics engine that specializes in letting programmers model terrain, flora, and water using relatively sparse data sets through the use of fractals."