A man who has been blind since birth "paints houses and mountains and lakes and faces and butterflies, but he's never seen any of these things. He depicts colour, shadow and perspective, but it is not clear how he could have witnessed these things either." Apparently, he is able to integrate the information from other sensory modalities, along with what sighted friends have told him about the world.

One tidbit from the article:

He confides that for a long time he figured that if an object was red, its shadow would be red too. "But I was told it wasn't," he says. But how do you know about red? He knows that there's an important visual quality to seen objects called "colour" and that it varies from object to object. He's memorised what has what colour and even which ones clash.

Neuroscientists at Harvard and Boston University have been running a number of tests which show some fascinating differences from (and similarities to) the visual cortex of normal sighted people. Here's the article as well as one of his paintings. Here are more of his paintings. (Via Linkfilter.)