Via Lifehacker: WinDirStat is a whiz-bang tool that scans your disk and organizes your filesystem in order of file size. The greatest feature here is that it also provides an incredibly intuitive at-a-glance display of just how your used disk space is allocated among your files.

Above is a shot of WinDirStat showing the disk usage on my system. The large blue area at top left is World of Warcraft (a lot of patch files hanging around there!), the red area in the middle is MP3s, the light blue areas are image folders. The green monsters at bottom left are my hibernate and paging files. Purple files are DLLs and yellow files are executables. Every directory is a rectangle of space, which is further divided into smaller rectangles of space for subfolders and down to individual shaded boxes for files.

Using WinDirStat, you can quickly assess where the big space users are, and delete them at once. It’s a much faster and prettier method than my previous technique, which involved copious manual use of du -h |sort -n in a Cygwin window.