Harvard's Nieman Journalism Lab produces a monthly roundup of "the top papers in digital media and journalism" and at end of each year compiles a list of "the best of the year." Coming in at #1 on their list of the dozen most important and influential studies of the 2013 on social media is Kalev's Global Twitter Heartbeat project, a collaboration with SGI and GNIP. See the full paper online with the full-resolution figures.