I had an interesting brainwave: individual markets. Players could invest in their own little market where they could set prices and such. (SS required?) Groups could band together and form larger markets, and individuals could invest in increasing the market size. After a market is created, the player can invest materials in the market and set rates for Naq/UU/Turns. (No PPT trading!) Larger markets can hold more goods and engage in more trades. At any time, though, the market owner(s) can close it and the goods are divided among the participants and distributed proportionally to each player's size and contribution.
I'd say an attack on a realm could damage the market, losing goods (nothing is taken from it, though-new covert ability?).
Basicly, a player could, for a sizeable amount of Naq (and possibly SS), make their own market. The owner could set the prices and exchange rates for the Naq/UU/Turns. However, the initial size of the market is small, so the player has to invest more money into the market to increase its size. Larger markets can hold more material and conduct more business.
Also, players could bank together to make a larger market. (This option is for alliances.) It might be possible for people to invest in multiple markets, but it might be wise to limit the number of markets a player can make.
In multi-player markets, it should be possible for any single person to close a market, but it should require the entire group to destroy it. The materials in a market are split among the members depending on how much they have invested in the market.
When a realm is attacked, it might be possible to destroy some of the goods in a market, but no goods should be stolen. Same for sabatoge. (This could be used for perventing the market form being used completely as a bank.)
.
.
