Treemap visualization is an excellent way to visualize the information/various metrics about the directory tree (e.g. source files directory tree). I have used treemaps for visualizing SourceMonitor metrics about entire project with excellent results. Unfortunately there are very few simple and opensource treemap visualization softwares available. There is JTreemap applet which can be use to view csv files as treemaps. Sometime back an Excel plugin was available from Microsoft Research site. However, there is no trace of it now on the Microsoft research site.
As part of Thinking Craftsman Toolkit, I wrote a simple Tkinter/Python treemap viewer to view the SourceMonitor metrics as treemaps. After writing initial version of Code Duplication Detector, I realized there is no good visualization tool to visually check the 'proliferation' of duplication across various files/directories. The tools like Simian or CPD just give a list of duplications. I thought 'Treemaps' can be excellent tool to visualize the duplication. Hence I added '-t' flag to CDD. This flag displays the treemap view of the Code Duplication. You can see the screen snapshot of the treemap view here.(See the thumbnail below)