Filelight creates an interactive map of concentric segmented-rings that helps visualize disk usage on your computer.
It is like a pie-chart, but the segments nest, allowing you to see not only which directories take up all your space, but which directories and files inside those directories are the real culprits.
If you want to have a filelight-style map prerendered at set times during the week, and then controlled in a web browser, take a look at Philesight, an excellent utilty that is also open source.
You can also browser remote servers using the fish:// or ftp:// KIO slave inside FIlelight, but for a system administrator I think philesight is more useful, check it out.
Installing From Source
You should be able to just copy and paste the following into a terminal:
tar xjf filelight-1.0.tar.bz2
./configure --disable-debug && make
su -c 'make install'