There has been a recent spike in the number of interaction networks graphed, with various degrees of novelty and usefulness.
Brendan Griffin has taken this trend to its logical conclusion by graphing every influential idea ever conceived.
Griffin explains his approach:
The node size represents the number of connections. To create the following graph I used a database version of Wikipedia to extract all the people with known influences. I then scaled the nodes by their degree of influence. The bigger the node, the bigger influence that person had on the rest of the network. Nietzsche, Kant, Hegel, Hemingway, Shakespeare, Plato, Aristotle, Kafka, and Lovecraft all appear as the largest nodes. Around these nodes, cluster other personalities who are similarly related thinkers/authors. I used a module to highlight communities in different colours which revealed sub-networks within the total structure. You’ll notice common themes amongst similarly coloured authors.
You can even buy yourself a print, called The Graph of Ideas here.