In addition, there are currencies being used to transfer value. but which are not accepted as legal tender. Such currencies include barter arrangements, time-dollars and travel-mile coupons.
The use of a single global currency is compatible with
the continued use of various types of complementary money
systems. One type is called ‘corporate scrip’, such as those
maintained by retailers. In Canada, the most famous is the
Canadian Tire Company’s use of Canadian
Tire Money with denominations similar to those of the
official Canadian dollar. Frequent flier miles, maintained
by most of the worlds’ airlines, are a type of complementary
Bernard Lietaer’s Theory of Money (summarized on web) has an exhaustive review of the various types of complementary currency systems. The review has numerous links to other relevant sites.
In Ithaca, New York, USA, the complementary currency called Ithaca Hours was started in 1991. Each hour is valued at $10.00 U.S. and Ithaca Money is printed in denominations of two hours, one hour, one-half hours, one-quarter hour and one-eighth hour.
For the view that private banks should be utilized more for the creation of money, see Why Private Banks and Not Central Banks Should Issue Currency, Especially in Less Developed Countries by Lawrence White and George Selgin.
See a list of resources on Free Banking and Monetary Economics for the view that money systems should be governed more by free market principles, such as having money systems compete with ech other like other goods and services.
For an alternate view of a global banking system based upon natural wealth, see the Global Resource Bank.