Saw this on ABC News this morning:
Fourteen-year-old Ben Underwood of Sacramento, Calif., is one of the few people known to use echolocation as a primary means of navigating the world on land. There's not even a hint of light reaching his brain. His eyes are artificial, but his brain has adapted to allow him to appraise his environment. He makes a "clicking" sound to communicate with objects and people around him.I'd seen something similar on TV a few years ago, this blind guy clicked and used echolocation to ride a bike, identify objects and even taught some other blind people how to do it.
Scientists have discovered that in the brains of the blind, the visual cortex has not become useless, as they once believed. When blind people use another sense — touch or hearing, for example — to substitute for sight, the brain's visual cortex becomes active, even though no images reach it from the optic nerve. Echolocation creates its own images.
This kid even manages to play video games, pretty amazing.
Here's an Wikipedia Article with some more links. The People article is better than ABC's.