You know what's popular? End of the world conspiracies, theories, etc.
I know you briefly talked about it in the "Bible Codes" episode. But there's more to it than just prophecies in biblical documents, etc. There's a ton of crackpot theories ranging from Meteors, to the sun spontaneously exploding.
You already have a good list of "future episodes" but I'm bored and decided to toss this out.