I recently made a template, which constantly calculates a new value of the Aorangëan Dollar. It is basically a sinus curve (to simulate periodical fluctuations) multiplied with an exponential curve (to simulate) inflation. I didn't do it because we need it, but rather because I can do it. You can see a table with "live" values here: http://wiki.opengeofiction.net/wiki/index.php/Aorang%C3%ABan_Dollar#floating Also in the list of currencies the value floats and therefore influences the sorting order.
If I might get bored and there is no public outcry here, I will introduce this for some more currencies. I did some blue currencies already.
If you like you can edit the parameters for your currency yourself, I added a minimum of documentation in the templates.