Miniature Black Holes
National Geographic has an article suggesting that mini black holes – on the subatomic scale – may be passing through the Earth every day. So anyone who thinks the Large Hadron Collider will destroy the Earth, read it.
The basic idea is that the subatomic holes evaporate too quickly to be of any real danger. It is thought that this occurs via “Hawking radiation” leaking out all the built-up radiation before they can grow to any size, although this radiation has not yet been experimentally confirmed to exist, to the best of my knowledge. Here’s a brief introduction.