Silver price 5 year chart
Silver. Source: Wikipedia
Silver (chemical symbol: Ag) has roughly 200 exploring/developing/producing companies listed on the two Canadian exchanges with a registered resource estimate. Silver is also a precious metal just like gold, but much cheaper, and its main purpose is for manufacturing goods.
One would say this would provide healthy supply/demand mechanisms, but this isn't exactly true as the price of silver is more or less connected to gold within certain ranges.