Via Freakonomics, Science News reports on a (7-year old) experiment that suggest that people can learn to see using their skin or tongues. Unfortunately, I can't seem to open the link to the original article (though it would probably be a little too sciencey for me anyway), but the underlying shift in thinking that makes it simple to understand is that people don't see with their eyes, they see with their brains. The eyes are just the conduit. So with training, we can process different types of stimuli as "sight". I'm guessing that the tongue is the best non-eye portal because it's so sensitive.
Not to sound all acid-trippy, but I guess this means one day we really will taste colors. Honestly, I know it won't happen for years and years if at all, but if this learning was mainstreamed, wouldn't that be so cool for chefs? Or really, anybody who likes to enjoy food.