For those of you who don't know - http://www.currencydebasement.com/ is a website that many of us use when we have curiosities about the metal content of foreign coins. It has a Legal Tender, Obsolute, and Redeemable database. But why most of us use it is it also has a Copper , Nickel and Silver coins database.
This week, they added a gold coins database to the website! I know that it takes an awful lot of work to put something like this together, I'd encourage the members here to check it out.
FYI - the owner of the website (who I do not know) is infact a member here.