I am looking for a list / source of the top 200 countries economies in
the world, ranked in order by GDP or whatever.

Hi! Thanks for the question.

Here is a link to the rankings by GDP for the top 231 countries based
on the 2003 figures of the CIA World Fact Book.

"GDP 2003"
http://www.photius.com/rankings/gdp_2003_0.html


Other economic rankings are available in the following pages.

"GDP - per capita 2003"
http://www.photius.com/rankings/gdp_per_capita_2003_0.html 

The Annual Economic Freedom Report is also a good ranking of economies
but unlike the GDP, the figures in the report only goes to the top 123
countries.

"Annual Economic Freedom Report" (Ratings are available at page 29)
http://www.freetheworld.com/2004/efw2004complete.pdf


Search terms used:                          
countries gdp rankings
countries prosperity rankings


I hope these links would help you in your research. Before rating this
answer, please ask for a clarification if you have a question or if
you would need further information.
                         
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Easterangel-ga                         
Google Answers Researcher