I know it's not fashionable in these post-crisis days, but have you ever thought of all the individual time and effort that gets saved when you replace a hodge-podge collection of bitsy currency rates with one? About the huge risk management - and paperwork - load it would from business as international trade flows grow as a percentage of the world economy?
As eminent Harvard economist, Professor Richard Cooper says, "by eliminating monetary and exchange rates as sources of asymmetric shocks among participating countries, a common currency will conduce to more stable economic activity ...."
We've learnt from the Euro's growing pains what to do and not to do; it's not rocket science. We could still keep local currency names for patriotic nostalgia; as many countries have done when pegging their currencies to the Dollar or the Euro.
Time to start thinking about a Dollar/Euro/Yen/Yuan/Real currency union. Serious.
Then we wouldn't have to worry about currency typos.