/m1 perhaps you're referring to Local Economic Transaction Systems (or LETS for short). Basically made up units of currency with no backing that are not interchangable for monies (that bit is for tax purposes mainly); everyone can apply for an account and start earning units or spending units - there will always be the same amount of overdraughts as 'savings', so the total sum of all the units is zero.
Getting into a little "debt" (there is no real debt of course, just negative bank balances) is encouraged to kick-start the system, as is spending what you've got.
Typically people get paid for services rendered, and not for products. For example, you might help painting my attick, I might help some old lady get along better with her computer, and she in turns bakes a wonderful weddingcake for you. Of course there is nothing particularly new about this; it's just a more sophisticated way of "calling in favors" or "giving something back to the community".
Also, in countries with hyperinflation, and not much "hard currency" to go round, people tend to invent backed-by-nothing currencies of their own (which usually collapse soon after when it turns out either the "legitimate" issuers or counterfeiters are printing huge amounts of free money for themselves).