How important and detailed is coinage and its usage portrayed in your games?
I'm interested in the subject, so I put a little more detail into it than I suspect is common. I don't think you *need* to; it's just one of those aspects that I enjoy.
Is it just a gold/silver/copper situation or do you have different names for the coins based on where and when they were minted?
In my current campaign, there are "coins of the realm" which are gold, silver, and three sizes/weights of copper coin. They have nicknames, but the use of the nicknames isn't that common, except for the copper coins.
Different realms have different coins, but it hasn't come up. The important part is the weight of the precious metal, in any case.
Is passing ancient coins from a crypt foray bound to raise eyebrows?
Sure. It will be weighed and accepted, but if it hasn't been seen, before, people will be curious where it came from (suspecting buried treasure).
Has a PC ever done things in a campaign that warranted their own visage appearing on currency?
Not in my current campaign (which is fairly new).
Has a mint ever figured into an adventure in some way?
No, but it's not a bad idea.
Please tell me all you can about coins in your games.
Well, I basically re-worked the values and prices for my OD&D game. I kept the OD&D ratio of 1 gp = 10 sp = 50 cp, set the coin weight as an ounce of precious metal, and then assigned "rough equivalent" values, so that I can think about the coins in terms of the dollar. A (one ounce) gp is roughly equal to $100, a sp to $10, and a cp to $2. I then set prices and wages and income levels based on those values. Modern economic values and fantasy world economies aren't directly comparable, of course, and there's still a lot of hand-waving in the whole thing, but it helps me out when estimating prices and such. I think it helps the players, too: when they slide a gold piece across the bar to the bartender while pumping him for information, they know it's like slipping him $100.
My OD&D price list is here:
Philotomy's OD&D Price List (pdf)