Update 2010.Feb.19: While reading about a proposed economic system called "Natural Money", I first learned of an ancient Egyption grain-bank. NewEco is similar except that instead of people depositing corn or other grains they perform labor, and their receipts are expressed in labor time, and when they later withdraw their labor-funds they get new services provided by the WebSite rather than their original grain/services back, and instead of being issued paper receipts they get a credit on their e-account.
But still, these funds, essentially "funny money", can be traded to other people for their services.
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Update 2011.Jan.03: Fixing The Future: NOW On PBS, hosted by David Brancaccio, describes a "time bank" in Portland (Maine), which is almost same idea as NewEco, except that David claims the IRS does not count their transactions as "barter income" which is taxed from both ends and where all transactions of more than one dollar must be formally reported (by the barter-system admin) to IRS within 24 hours. TOP