Nintendo's Light Telephone (オプトエレクトロニクス 光線電話LT, 1971)

The Light Telephone must be one of the most unorthodox of Gunpei Yokoi's ideas to make it into production (the Chiritori toy vacuum cleaner being another candidate for that title). Like the Kousenjuu light gun series, it demonstrates very creative use of solar cells. For info on the Light Telephone check out http://blog.beforemario.com/2011/06/nintendo-light-telephone-lt-1971.html