Awesome topic, I love it!
I love to throw in special currencies into my games. Here are some of the ones I can remember:
One of my favorite settings was a Steam-Fantasy world that relied on a special material for it's furnaces to function. Similar to coal, yet it only formed in hard to reach, out of the way areas that seemed touched by the otherworld. The Arkencoal was, in fact, the solidified souls of the departed. It burned ten times hotter than coal and people that slept near an arkencoal lamp or device would often experience strange dreams that belonged to other people. Of course, the Arkencoal was measured in weights, but it was considered the most precious substance in the world.
One of the countries, Illsandor, was the strongest in military and steam-technology, and was ruled by a Rose-Queen. The Rose-Queen is protected by her Thorns, elite guards that can only be replaced by being bested by any member of the kingdom, and the Rose-Queen never married, but had daughters who were the priestess' that acted as a veto to the Queens power. Anyway, the coinage was based on this system of government, as everyone loves their Rose-Queen.
The Clip - "Clip" "clips". The smallest demonination. A simple, small lead length fashioned to look like a clipping of a rose stem.
Petal - Petals are small copper "coins" shaped in tear shapes. These are the Petals of the Rose-Queen, her love that falls to the earth for the common folk. The most used coin.
Thorns - The Thorns protect the Rose Priestess' and the Rose-Queen. A silver cut coin that is made to be almost sharp, like a thorn.
Rose - The Rose is a large sized, beautiful golden rose, complete with petals. The Rose can be cut along the petals to form 5 seperate "Daughters". Representing the Rose-Queen and her daughter-Priestsess'.
Rose Crown - The Highest coin, and most of the citizens never see one in their lives. Rose crowns are gold chased platinum petals, linked together like a crown of roses.
Another place, a magical country known as Esterfay, ruled by a noble-mage counsil, issued a special form of barter/trade coinage, below:
Mark - Marks have variable value, but anyone knows a mark's value when they see it. A Mark is a magical tattoo, a winding arcane symbol that can be transfered willingly between two parties. The tattoo migrates from the owner to its new owner after the two clasp hands and agree upon the amount. Marks are based off of the Mage-Noble families magicial essence. Long ago the noble families began purchasing the life energy of its citizens in exchange for wealth. The marks are simply a faster means of trading the life energy. One small mark can be worth a minute of life, where as some are worth an entire year.
The Marks are of little value to a common person, who cannot redeem the magical essence from the tattoo, but they are traded to the noble families and the tattoo "coinage" trickles back down into the system.
Brea - Originally refered to as a "breath of life", these are complex matrixes of glass and precious metal that a large quantity of magical essence. They appear as two inch helix shaped silver bars twisted around the shimmering green gemstones within. A single Brea is worth a standard of 50,000gp.
