Every month we make hundreds of millions of SERP requests across 40 major markets.  When we find influencers ranking, we annotate our database and link the related data together in a graph database so the relationships are easy to explore.
We then supplement this by looking for named contacts on the key pages that are ranking for your monitored keywords in your project.  This gives us breadth and depth of contacts to go after in almost every conceivable niche.