The venerable Lawrence Watson alerted me to this fantastic demonstration of the power of mega-data that has been neatly displayed with appropriate graphics.
The amazing thing is that Facebook friends do not happen at random, and despite what many think, reflect something of the true social structure in the world. What this shows is a trace left behind by migration, holidays, and study abroad stints.
As Michael Clemens points out on Twitter, this presents massive research potential. Simply making these connections should be almost impossible, and yet people have volunteered to enter it into an accessible database. All that remains is to ask it questions.