(this is a blog, not a podcast)
zefrank does some simple GIS mapping to identify places in the world that are exactly opposite from one another, and contain land (not water/ocean). The reason for doing this is so two slices of bread could be placed on opposite sides of the earth to make an "Earth Sandwich." Interesting idea, even more interesting map.
In general, it is surprising just how much of the land area of the planet does not have land areas on their opposite side of the globe. We are, indeed, a big blue marble made up mostly of ocean water! (Note that the big yellow of Greenland looks huge on this map because of the Mercator projection, which spreads the north and south poles out enormously. Greenland is actually smaller than Australia.)
According to the website:
"Possible sandwich locations: The duckie-yellow areas are places where it is possible to make an Earth sandwich such that both pieces of bread are on land. It may not be exact, but it's pretty close. In some cases, islands that should be yellow are too small to be seen on this map."