I've been having huge fun with an Android app called FindShip, which allows you to instantly locate pretty much any ocean-going vessel. It plots the ship on a map and gives you some basic info about what kind of boat you're looking at.

What got me interested was a claim by the owner of the ship Odyssey Explorer that the position of his salvage operations were being published on the net in near real-time, which he felt was a gross invasion of privacy. First thing I did with the app was locate his ship. The Streisand Effect in action.

Naturally, the second ship I looked for was the Maersk Alabama...and there it was off the coast of Africa, not far from Somalia. Some people never learn.