I always feel networks and trees are the most “humane” visual encodings in the visualization world. You may ask why, because all of those visual encodings represent relationships between objects and relationship is the core of everybody’s daily life.
Given the nature of those kinds of encodings, trees and networks displays their strength in solving a lot of real life problems. One of the interesting demonstration can be seen here. We are also trying to build an anime visualization (coming soon) which is used to answer questions like similar animes using those visual encodings. And they are also widely used in Genealogy and Biology.