The other day somebody asked me how "far" I could "talk" using Amateur Radio.
The obvious answer was half-way around the world, depending on band conditions.
So then I started thinking (I know, a sometimes dangerous thing with me), where, exactly, was "Half Way Around The World"?
Well, the point that's "half-way around the world" from wherever you are is called The Antipode, and of course, there's an app for that:
It's a pretty neat little webpage, and it's located here.