Minnesota-based Andersen's new entrant, which isn't for sale yet, is a bay window that doubles as a home entertainment center. A low-voltage electric current runs through the window. When the current is on, the window is clear. But flip a switch to turn the current off and the glass goes opaque, allowing it to be used as a projection screen for watching television or DVDs. The flanking casement windows become the speakers.
http://www.washingtonpost.com/wp-dyn/articles/A19548-2003Jan20.html