Neat, although I'm not sure why it's sideways -- typically Mercator is displayed with the distortion extending vertically. Type in "north pole" and you get the projection that you see on maps -- but turned 90º.
Also, it be nice to have it reversed -- when you type in, e.g. "Cambridge MA" it would be nice to have a map that's most useful for Cambridge, versus being most useless for Cambridge. But I guess this way is more fun, and forces you to consider the distortion more.