"E-mails tend to flow much more frequently between countries with certain economic and cultural similarities."

While exploring possible social network projects, I came across this little nugget: http://www.washingtonpost.com/blogs/worldviews/wp/2013/03/07/an-incredible-map-of-which-countries-email-each-other-and-why/

Basically, it's a social network of countries, with the strength of the ties between countries reflected by the volume of emails between the countries. The findings suggest that that analysis provides support (though qualified) for Samuel Huntington's "Clash of Civilizations" argument.