This utility written by Jocelyn Turcotte is an IronPython program that leverages Windows Presentation Foundation (WPF) and System.Windows.Forms to create a handy utility that graphically displays disk usage information. The readme.htm file in the download (download page: IronPython-1.0-Samples-DiskUse.zip) will get you started.
When the application is first launched, a file dialog prompts you to pick a base directory. This is the directory that will be analyzed. Once a base directory is chosen, the application scans the file system to retrieve the names and sizes of subdirectories and files. The utility displays the directory and file information with a treeview in the left pane and a graphical presentation of the relative file size information in the right pane.