An isometric word cloud showing depth (as height) and number of instances (as area) of the nodes of DBpedia’s hierarchical ontology. Although it represents a tree and uses a treemap algorithm, this is not a real treemap: Hierarchical relations are not represented at all, since nodes are ordered only by depth and number of instances (i.e., siblings may fall into different parts of the diagram).
Unfortunately, the treemap algorithm does not succeed in making good aspect ratios for certain rectangles with a small instance count. In a 2D treemap, this would have completely no visible effect (except for hiding the class, of course), but with 2.5D we get ugly parallelepipedons with a really elongated top face. Also, some labels are barely readable because of a mismatch between string length and aspect ratio.
Despite these considerations, the diagram can be used to see the relative size of DBpedia’s classes (in term of their child instances) while intuitively take their depth into account.