The Washington Post reports that by analyzing more than 10 million emails sent through the Yahoo! Mail service in 2012, a team of researchers used the R language to create a map of countries whose citizens email each other most frequently:
The chart above shows the top 1000 country-country pairs by email frequency, arranged in a clustered network using the R igraph package. While it's not surprising that countries that share proximity, language and culture might tend to email each other more often, it's interesting that the clusters tend to resemble those of Huntington's Clash of Civilizations, whose "major civilizations" are used to color-code the map. (A formal test of similarity was done using R's SNA package, with country-specific factors corrected for using a linear mixed-effects model.) On this point, the authors write:
In this respect we cautiously assign a level of validity to Huntington’s contentions, with a few caveats. The ﬁrst issue was already mentioned – overlap between civilizations and other factors contributing to countries’ level of association. Huntington’s thesis is clearly reﬂected in the graph [above], but some of these civilizational clusters are found to be explained by other factors ... The second limitation concerns the fact that we investigated a communication network. There is no necessary “clash” between countries that do not communicate, and Huntington’s thesis was concerned primarily with ethnic conﬂict.
Indeed, the validity of Huntington’s ideas with respect to ethnic conﬂict has come into controversy, and we limit ourselves to showing the validity — at least partial — of this division for communication networks.
The Washington Post article (linked below) has more discussion about the research, and you can find details of the methodology in the arXiv paper.
Washington Post: An incredible map of which countries e-mail each other, and why (via reader GF, with thanks)