What is the use of these \'Mithril Pieces\'
Only the future knows the real answer to the question, but for now we have a monetary system whose main use is for message postage. You can also move from one location to another for a fee of 400 pieces of Mithril. In the future there will be other things to spend mithril on and other methods of gaining it, such as on birthdays, for writing articles, winning contests, etc.
The membership will be asked to participate in generating ideas for this as we build up our communities. We may need (were we to be a true simulated world) to buy seed for planting crops to be sold to pay for a plow, and for the miller to grind the grain for the baker to bake the bread to sell to the dairyman who needs to pay the haymaker and the cobbler, etc, etc, etc. We may even, heaven forbid, need taxation to support some necessary evil, like the bounders or an army to keep the outlanders at bay.