http://gt5.sourceforge.net/
This project is simply amazing. The download includes the binary and other files. Simply execute gt5 from where it is extracted or more wisely place it in /bin/gt5 so you can run it from anywhere. You can specify any directory (ie: gt5 /).
*stores previously ran information and will show you the different (in bytes)
*very nice easy interface
*largest (percentage) at the top to narrow down where the disk usage is
*runs on nearly any system with included utilities (du for example)
Output is done in HTML and easily shown after parsing with the included tool, again with the simple execution of gt5 /
It took a bit of digging to find a good program that would work directly in the shell for headless machines. This one is simply fantastic.
EDIT:
gt5 is still pretty good but it’s not as easy/fast to get installed. Recently I’ve been using ncdu thanks to this question/answer. There are CentOS and Debian packages in their repos. ncdu homepage.