I did have a little idea about this - and just now remembered to post -
If problems with duping are solved as someone previously said in the thread. Then why not add an item (such as a Knut) that can be bought for an amount of virtual gold and then sold back to the vendor for the same amount of gold - If this could be implemented without the possibility of abusing the system - it would create a form of physical currency for those who want it! Kind of like you were able to buy glass and sell it back for a smaller amount, but keeping the amount the same.
If problems with duping are solved as someone previously said in the thread. Then why not add an item (such as a Knut) that can be bought for an amount of virtual gold and then sold back to the vendor for the same amount of gold - If this could be implemented without the possibility of abusing the system - it would create a form of physical currency for those who want it! Kind of like you were able to buy glass and sell it back for a smaller amount, but keeping the amount the same.