hmm...in 2002 I managed to do this in just under a month:
Canada-Netherlands-UK-Denmark-Sweden-Finland-Estonia-Russia-Belarus-Poland-Germany-Netherlands-Belgium-France-Belgium-Luxembourg-Germany-USA-Canada
so thats 15 countries in 30 days.
This past month I got to
Poland
Netherlands
Canada
USA
United Arab Emirates
Malaysia
Thailand
Singapore
Australia
New Zealand
so I need 2 more for 2003 to get 12, but I agree with some of the other posts, people from down under should get a 5 country head start, its so much easier in Europe!