WinDirStat Home Page:
"WinDirStat is a disk usage statistics viewer and cleanup tool for Microsoft Windows (all current variants).
* WinDirStat reads the whole directory tree once and then presents it in three useful views
* The directory list, which resembles the tree view of the Windows Explorer but is sorted by file/subtree size,
* The treemap, which shows the whole contents of the directory tree straight away,
* The extension list, which serves as a legend and shows statistics about the file types.
* Coupling. Select an item in the directory list: The treemap highlights it; and vice versa.
* Built-in cleanup actions including Open, Show Properties, Delete.
* User-defined cleanups (command line based).
* Works with network drives and UNC paths.
* 'Create disk usage report' option.
* 'Submit bug report/Feedback' option.
* Online help.
* Language can be set to English, German, Polish, French, and Russian.