If the links between node could be directed and annotated, then it'd become much more powerful, though. Similar to how TheBrain works [1]
I see that the public plugin interface is a long term goal at this point [2] but it'd be amazing if plugins could expose ways to mark up graph relationships!
[1] https://www.thebrain.com [2] https://trello.com/c/Z7qqKVXd/19-public-plugin-interface-v10