WinDirStat provides a visual and statistical representation of disk usage, as well as cleanup tools. It reads the whole directory tree once and then presents it in three useful views: directory list, extension list, and tree map. Its built-in cleanup actions include open, show properties, delete as well as user-defined ones.
Note: The 98/ME version works on all versions of Windows but does not support Unicode. The 2K/XP version only works on WinNT and higher.
Alternatively, WinDirStat Portable and X-WinDirStat are also available.
