This is what I envision as a "good" Fallout MMORPG:
In the game, we start with tribes with no clear leadership. These tribes are not necessarily cave tribes, they could be city tribes. Anyway, the game first assigns you several simple Quests and whoever gets the highest score in the tribe wins the title of "Mayor".
The Mayor has the power to form 1 Town and can create Quests and assign Sheriffs. This way, you reward players for playing correctly, and you get to punish players via the Sheriff. For example, a quest would be "Show mike681 and his gang a lesson."
Fallout MMO should allow the Mayor to choose his government (Raiders, Democracy, Republic, etc) and allies/enemies. The Mayor chooses how long he wants to govern (lifetime or terms). The choices of government and the amount of allies are enhanced by the Mayor's intelligence and charisma, but are ultimately determined by the relationships he establishes with other Towns.
There is only a limited number of Mayors. Once all the Towns are taken, players are assigned to an occupied Town, where they get to choose their special perks and characteristics.
Players should be able to easily form Groups or Clans to fight the government, or to achieve whatever goal they want (a merchants/drug group, or a prostitution ring, for example). Each Clan should have an interface similar to that of a Mayor, but obviously without access to the Sheriff.
Also, commerce should be an important aspect of the game. The more commerce in a town, the more police officers the sheriff can hire, and the bigger guns they can get. Therefore, there would be an incentive to protect the merchants (including drug runners and prosttutes).
You should be able to choose to be a child and gradually "grow-up" into an advlt.
You should be able to enter dialogue windows, and not just see floating text bubbles, and I'd be nice if we could have webcam and microphone support (although unlikely).
You should be able to kill ANYONE in the game. If the Mayor is assassined, the Sheriff has to decide something quick (he doesn't have the powers of the Mayor, he has to assign someone or himself to be the mayor). The Sheriff should be able to kill the Mayor, and there should be a bribing system in the game.
The way you level up is by doing quests and joining Clans.
Also, a nice little feature that I always wanted to see in Fallout 2 is an auction. If there is a rare item in the game, they owner should have the ability to auction it. Merchants should be able to establish a whatever business they want, whether it's selling Iguana-on-a-stick, or a "Bathhouse".
People should be able to be captured/enslaved/kidnapped, and then sold.
If all of those are in the game, I will gladly pay up to $25 bucks per month. The main idea is that I don't want a repetitive game. I want a game where the players truly decide how the game is played.
Anyway, post your comments to my ideas, and post your own visions of how the Fallout MMO should be.