I've invested quite heavily in my trade skills, I have 100 smithing, 90 enchanting and 80 speech. I can invest money in stores, sell stolen good to everyone and have any merchant buy any type of item. This is great, but there's potential for so much more.

Skyrim is dotted with little villages, each with their own economy. There need to be some more visual cues as to how well these communities are doing. As a small farm begins to increase in prosperity things should change. A dirt road should become partly paved, the facilities available should, likewise, expand. That small town with just a grindstone now has a forge with a blacksmith working full-time. The more money you invest in his business, the better his personal assets and facilities become. His house gets another floor, his work area is enlarged and he has more money to spend etc...

Similarly, you should be able to set up your own shop. Give an NPC some goods to sell and see people coming and going from your little store (which, initially could be a small stand in a market place). You could then buy a proper store, or have one running form your home.

The holdings of farming villages should increase, more guards, more land, more crops, more residents. This would allow for some interesting randomly generated quests dealing with corruption. It's a great way to make a lasting impact on the world and provides a cash sink for the rich to entertain themselves with.

The sky's the limit, you could invest in anti-dragon equipment, employ guards to use them etc...

You should never be able to become mayor though you can become a 'benefactor' or something similar with various entitlements. Once you've done enough to aid the world of skyrim as an investor, the monarch (whoever it is in your game) should bestow rewards upon you. Perhaps even task you with establishing your own small village in a small set of locations, only then would you 'own' it (and with it, take quests to influence its growth and running).

Just an idea.

The idea sounds nice, but is near impossible to implement, the amount of work in that alone would be enormous, because with added size comes added threats. New quests that should be handled. New NPC's moving there, or NPC's moving from somewhere else to there... Unless magically people start appearing there would be something wrong with the system.

More true to the game however, would be the fact that all of the events in Skyrim happen in at most a year... There is no way such large changes would happen in such a small time frame.

How dynamic the system is would be left to the developers. Even if it was limited to a few locales which were scripted to behave in the way described would be something to be getting on with. :]

Edit: I'm sure that there are plenty of Nord ex-patriots willing to move back into Skyrim. Similarly, refugees from other provinces could also trickle in. Hell, smuggling those people in could be a quest line in itself.