Commemerative Silver

What is the value of one troy ounce of silver?
commemerative coin
As of 6 January 2007, silver is worth $12.12 per troy ounce. Presumably, your coin has some value as a collectible in addition to that. Without knowing what type of coin, I cannot say how much more than bullion value your coin is worth.
The link below is online up-to-date gold and silver spot quotes.
Exceptionally tasteful 9/11 commemorative dollar ad