Above is a visualization of angel investing activity in Pennsylvania, based on the AngelList API. I made it (using Ruby and R) to get an alternate view of local investment activity. Each vertex on this graph is an investor. Each edge is a co-investment.
I've decided, in this case, to hold back the detailed analysis, but it was quite interesting. Unsurprisingly, the most well-connected investors in the area are (as measured by eigenvector centrality) First Round Capital, Josh Kopelman, Gabriel Weinberg, and Kal Vepuri.