Ken Webb 2010-04-23T17:02:59Z
Treemaps "display hierarchical (tree-structured) data as a set of nested rectangles."
Any Xholon application, or subtree within an application, can write itself out as an XML file that can be read by the open source JTreeMap, and displayed as a treemap.
Cascaded treemaps look like an interesting variation. They capture the structural hierarchy in an easier to understand way, while retaining the basic benefits of a treemap. I don't know if any available tools support cascaded treemaps.