One of my guilty pleasure TV shows is FOX's "Fringe". It's a compelling sci-fi show that sometimes deals in real world science and scientific mystery. Last night's episode, was about a unexplained phenomenon called "Number Stations".
Since the late 1940's, these shortwave radio stations have been broadcasting a seemingly random list of numbers for anyone to hear, usually those with a HAM radio. There are thousands of enthusiasts around the world who listen to and track these odd broadcasts but no one has been able to crack their code. For years the rumor was that these stations were broadcasting the secret messages of spies during the Cold War. But the Cold War is over and the numbers stations persist. No government has officially ever admitted to using numbers stations.
The explanation on "Fringe" last night had something to do with agents from an alternate universe giving longitude and latitude clues about where to find pieces of an ancient, buried doomsday machine that, if re-constructed, may likely destroy this universe. Cool, right? But if you'd like a more real explanation, I found this CBS News report on YouTube which has some interesting details and a more in-depth report on NPR.