Minecraft wiki entry for Building_a_metropolis, associated text: Syndicalism
A potentially more workable way of anarchy.
No central government, no banks, no money (players will have to find a way to trade!).
The economy is run by a council consisting of players representing every part of the economy (potions, farming, cobblestone, etc.); these council members are democratically chosen and represent their industry's workers, but have no more power than the average member of the community.
No one "owns" any land, not even the council members. Since there is no government, there's no police force to protect private property.
There are no laws. However, banning is still an option in case of hacking, etc.
If anyone doesn't like the city, they can just leave, since there is no government.
Do anything possible to make sure that no one player has more influence than any other (no social or economic hierarchy), but always have the ban hammer at hand to keep things from getting out of control.