The Italian village of Viganella spent many months in both darkness and the cold during winter as the sun was obstructed by surrounding mountains. Some of the 185 villagers decided to do something about it. Their solution was to build an enormous eight-by-five meters (26-by-16 feet) mirror and install it on the side of a mountain. The mirror is controlled by a computer to follow the path of the sun and ensure that as much sunlight as possible is reflected back to the village. The project took some seven years and about 100,000€ to build but ask any of the villagers if they think it was worth it and I bet the answer will be a resounding yes.
Source: Engadget