Hi, first of all, English is not my mother language so sorry if I repeat a lot some words. I should apologize too if that's not the way you like the links: I can't find a way to atach a link to a custom text (<a href="link">text</a>).
There's another free software project that competes with conventional money(http://www.openmoney.org/
This software let you create a mutual credit currency(http://en.wikipedia.org/wiki/Mutual_credit
). But you need to run a centralized server for that.
Mutual Credit Currencies are well suited for small communities in which everybody knows each other.
In a mutual credit system, any issuer of the currency (I think that normally everybody in the community is an issuer) can create money just by buying a good or service to another user of the currency. The seller then increments his balance in the amount that the buyer's one is decremented. The issuers can have a negative balance only limited in time and quantity by the rules set by the community. That currency is therefore backed by the goods and services offered by that community.
I think openmoney has two main flaws. Both are related with the need of a central server.
1) A central server can be easily closed down by the authority above the community.
The central banks don't usually like to have local currencies in their "territories". Here's(http://en.wikipedia.org/wiki/Wörgl#The_W.C3.B6rgl_Experiment
) one example. That wasn't a mutual credit currency but a fiat currency with demurrage(http://en.wikipedia.org/wiki/Demurrage_(currency)
). What Silvio Gesell(http://en.wikipedia.org/wiki/Silvio_Gesell
) called free money(http://en.wikipedia.org/wiki/Freigeld
2) There's not an easy way for the different communities to exchange with each other. The server's aren't interconnected and one have to be accepted by the community to even accept their currency. Well, you can accept their printed currency (sometimes they have an account to which the members can pay an amount of digital currency in exchange of the same amount of the printed currency or pay in printed money to get digital) but not the digital one without an account in the central server.
To exchange between communities they just have conventional money which they don't like (neither me).
Bitcoin could be modified to record transactions in different currencies. Each currency would have a pair of keys so the creator of the currency could sign a file with the properties of the currency and a list of public keys that are allowed ti issue it. The creator could also sign another documents describing the currency to improve its acceptance.
Anyone could be a user of any currency but no one will be forced to accept any of them. A market between currencies could be implemented within the network just by allowing bidirectional transactions between currencies. No third parties would be required. Maybe the implementation of that last thing is not an easy problem and it's not very important, so don't concentrate on this. Third parties for exchanges (like now with bitcoins) could be a simpler and better solution.
One possibility is coding a fork of bitcoin with these qualities. The problem is who would run the nodes. The solution would be creating an inter-community currency to pay the nodes fees. That money could be created for some time just like bitcoin is. This currency would be great to simplify exchanges between the different community currencies too.
What I think is Bitcoin itself could be that inter-community currency. I wish a fork could be avoided.
What would Bitcoin community win?
Users, for sure. I think some communities would run nodes too (instead of their central servers) in order to earn bitcoins to pay for the future fees and to commerce with other communuties.
What I think is the biggest problem is the implementation of a transition from the current bitcoin network to a network that allows different currencies.
Would it be possible to maintain the actual balances of bitcoins in the proccess?
I want to hear what you think about having a single network with multiple and diverse currencies.