WinDirStat is a tool you can use to keep track of “who’s on first” on your hard drive.  Along with a standard directory listing, it’s also got a “treemap”, a graphical way to represent files with colored rectangles that show relative sizes of files on your system. (It may actually make more sense when you look at it than it does when you hear it described.)

Along with looking at your files, this app lets you manipulate your documents as well, with Open, Show Properties, and Delete actions built in, as well as allowing you to create your own. You can generate disk usage reports as well.

Description supplied by freedownloadaday.com

WinDirStat