In the net art piece "TimeStream," the first online work by video artist Tony Oursler, a website is turned into a dark, mysterious environment where flickering, ghostly faces serve as elements of the homepage's user interface. Oursler's site -- the first work of net art commissioned by New York's Museum of Modern Art -- allows visitors to explore such varied topics as ancient Egyptian modes of communication, the camera obscura, cathode-ray tubes, and X-ray devices -- a loose history of media.