In the world of ancient coin collecting, there is a project that has been ongoing for several year. It is the "NumisWiki" at forum Ancient Coins
http://www.forumancientcoins.com/numiswiki/view.asp. It may be worth looking at,but they don't deal with new coins or paper notes.
One of the problems I have seen with most modern coin references, is that there are so many, and most don't give a number to each coin in a series, say the the American Lincoln penny. They note the deries, 'wheat ' or 'Lincoln Memorial' and may change with the copper vs copper clad zinc, but each year and mint are not assigned a number. One of my side collections is the roman Provincial PMS COL VIM, and one of the best references I have come across is a book buy Martin who revised the older book by Pick. They used a decimal system, like 1.1.1 which would indicate Gordian III, sestercius, and some variation of one style. the nice thing withthat system is that recognized variations [mostly legends] could be easily noted and added without changing the entire numbering system. Changes in the 'artwork' or size/type would change the second place numeral, the first digit was reserved for the Emperor.
Bruce
