Required Reading:
Eric Helleiner, "Why are Territorial Currencies Becoming Unpopular?," Working Papers of the Trent International Political Economy Centre (2001), on-line.
W.G. Wolters, "The Euro: Old and New Boundaries in the Use of Money," Anthropology Today (Dec. 2001), 8-12. [JSTOR]

Further Reading:
Michael Bordo, "Is there a Good Case for a New Bretton Woods International Monetary System?" American Economic Review 85:2 (May 1995), 317-322 [JSTOR].
Gerald Dwyer (Federal Reserve Bank, Atlanta) and James Lothian, "International Money and Common Currencies in Historical Perspective," (2002), on-line.
Barry Eichengreen, "European Monetary Unification," Journal of Economic Literature (1993), 1321-1357.
Eric Helleiner, The Making of National Money: Territorial Currencies in History (2002).
Andrew Martin and George Ross, eds., Euros and Europeans: Monetary Integration and the European Model of Society (2004).