When a server at work that should have had gobs of free space suddenly claimed to be running on empty and we wanted more info than we could get from the find command, I discovered this little gem: Disk Inventory X, which quickly drew a map of files and folders on disk by type and space. Culprit turned out to be a 305 GB log file generated over the past few days by an out-of-control Samba process.
Pictured above is the main drive in my home Mac. Rectangles are files, and their containing rectangles are folders. Each color represents a different file type. Select a rectangle and it’s immediately selected in a corresponding file tree (not shown), and vice versa. The region selected in yellow represents my old unused OS 9 System folder. Trippy. And useful.