Disk Inventory X is a disk usage utility for Mac OS X (10.3).
It shows the sizes of files and folders in a special graphical way called "treemaps".
If you've ever wondered were all your disk space has gone, Disk Inventory X will help you to answer this question.

Finder context menu plugin with a "Open in Disk Inventory X" command for folders and volumes (have to be installed manually in the preference window!)
a new selection list which can show all files of a specific kind or all files (to show the selection list, use the new context menu in the kind statistic or select menu "Window->Selection List").
an option whether the assignment between colors and file kinds are shared between open windows or not (so every kind has in all windows the same color - like before - or the assignment is done for each window separately)
performance improvements when dealing with a large number of files
sortable columns in the kind statistic drawer (and in the new selection list, of course)
a warning is shown prior deleting a file or folder on a network volume (items on a network volume can only be deleted, not moved to trash)

bug fixes:

DIX crashed when refreshing a file or files if DIX has zoomed into a folder
the "select parent" shortcut did not work if the file view had the focus: the shortcut is now changed to Apple-U (previously Command-P).