Disk Inventory X is a disk usage utility for Mac

If you need an easy way to check your disk usage on Mac. Look no further. Disk Inventory X 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.
The best thing is it is totally free.
You can download it from http://www.derlien.com/downloads/index.html