by Rick the collector on 02 Jun 2009, 12:02
Until present, 29 mintmarks and 18 mintmaster marks have been used, according to the information on this site.
However, many of them were double use (Monégasque coins for instance have the same marks as France) and Lithuania was also in the list, which is not an EMU member yet.
In my opinion the correct answer is (so with correction of double use):
18 mintmarks
11 mintmaster marks.
As an answer to Miguel (again I'm not 100% sure): all three types of letters you mentioned (S on Greece, F on Malta, Fi on Slovenia) matter, since they have been incorporated in this Website's topic on mintmarks. However country identifiers on their own coins, such as BE on Belgian coins from 2008 and FI on Finnish coins from 2006 don't count, since they're country identifiers and not considered marks.
Regards,