Now is not necessarily the time for Americans to visit France as the dollar is not at all strong against the Euro at the moment and; therefore, Americans have less spending power there than some years ago.  The Euro, also referred to as la monnaie unique in French, was put into circulation back in January 2002.  So far, it doesn’t seem that a good slang word or mot d’argot has been devised for this European currency like balle which was used for the French franc.  But, I have seen some proposals such as jeton and some of the French still talk about balles and pions, although one wonders if they are thinking in Euros or francs…
Belgium, Luxembourg and Monaco, where French is also a national language, use the Euro as well. However the other European French-speaking country, Switzerland, does not use the common currency.  The national currency of Switzerland is the Swiss franc.
Here is a list of French-speaking countries and their currencies: