Recently published in Nature, research by Chetty, R., Jackson, M.O., Kuchler, T. et al. suggests that economic connectedness, or friendships between rich and poor, could improve economic mobility. The researchers used Facebook connection data from 70.3 million users, along with demographic and income data. NYT’s The Upshot explains the relationships with a collection of maps and charts.
You can find an anonymized, aggregated version of the data through the Social Capital Atlas. Also, I am very much into this socially-focused use of social media data.