One of the problems for medium-mana and high-mana users is that almost all markets either have low trading volume, or take months/years to resolve. If you want to make a profit, there is little option other than dumping all your mana into these long-term markets, and then coming back to the site months later to reinvest. (Or, more likely, forgetting about the site altogether.) My idea is to have a "Market of the Week" tab which contains a market which resolves at the end of the week. It would be chosen by the mods, based on what they think would be most engaging and informative given current events. This way traders can compete in a market which is both short-term and high-volume.