This morning I found a cool site featuring an interactive map called the Antipodes Map. What you can do is find your home (or any other place on the map) and the map will show its antipode - meaning the spot on the earth of which it is diametrically opposite. As the site explains, "Two points which are antipodal to one another are connected by a straight line through the centre of the Earth."
Therefore, if you click on, or move the original map, you can set a marker on a desired
location. The antipode map will automatically show its antipodal
location. So what can you use this for? Well, most importantly, it will show you where if you dug straight through the earth you'd end up (provided of course you were able to withstand all the radiation, heat, and intense compression you would experience).