Disk Inventory X is a disk usage utility for Mac OS X (10.3 and later). It shows the sizes of files and folders in a special graphical way called “treemaps.”
If you’ve ever wondered where all your disk space has gone, Disk Inventory X will help you to answer this question.
Disk Inventory X is free and released under the GPL.
More info, screenshot, a link to a one minute video about the app, and download link here.
[Thanks to MacDailyNews Reader “LinuxGuy and Mac Prodigal Son” for the heads up.]