I remember reading a blog post a long time ago (forget link) that claimed that centralized currencies allowed positive feedback in that the rich got richer while the poor always had to scramble by.
Centralized currencies allowed the rise of aristocrats to become wealthy even though they did not provide value (e.g. create shoes, fight in battle, build houses, etc...) The previous barter economy of course had problems of itself.
My economic background is too weak to grasp this strongly but I think there is an interesting point here. I was just reading a post on how a new user was frustrated at getting enough votes to start using SOs features.
Perhaps a new model of "currency" would be interesting. (Not necessarily for SO, just as a general idea) Maybe each user would start with a certain amount of "units of whatever"(UOWs -> WOWS) and people could exchange WOWs (like the current bounty system except as a core feature rather than an added feature) for answers. When an account becomes "bankrupt" all its posts could be deleted (or ranked down, or have the default text color be white, etc...) Questions would also require "upkeep" in that each question would drain slowly and eventually disappear unless people donated to its "repair". Really good questions could be placed on "historical significance" list with no upkeep cost and the top 7 would be know as the "7 Wondrous Questions of Eternity"
Just some random thoughts :)
EDIT: Yeesh! so much negativity on an idea that isn't necessarily for SO
EDIT2: Think of how an economist would see votes. Votes are valued. Votes equal prestige. Votes can only be transferred in unit sums from person to person and only once. Votes do not require sacrifice to give. How liquid is this economy? How easily do the richest amass their wealth and what percentage of all the wealth do they own? I think this is a very interesting question...I am not saying we should change SO I'm just wondering why every forum is copying Reddit's(or whoever) upvote thingy without understanding the human dynamics it creates.