If you dig a hole through the earth, where will you end up? Check out these websites for the answer. They're both a clever use of Google Maps.
With this map, you can click anywhere on the map and you'll get a "Dig here" link. Click the link and a push-pin shows you where you'd end up.
This one has two maps side by side. You can drag one and watch the results in the other.
And we were always taught we'd end up in China.