Human echolocation

I know, that's what I said. WHAT?

But apparently it's real. There are documented cases of blind people using echolocation, much like dolphins and bats would, to navigate their worlds. These people make clicking sounds with their mouths, and are able to decode the sound of the reverberations to determine the spatial locations of objects. Interestingly, they seem to be using the visually oriented parts of the brain to accomplish this distinctly auditory feat.

Here's a journal article on the subject.