Due to popular demand, and just because it's a nice KDE application that does a similar job as what I covered last time, I'm now going to show you Filelight.
Filelight bills itself as a program that "creates an interactive map of concentric segmented-rings that helps visualise disk usage on your computer". In essence, it's a graphical program that helps you look at and understand how much space different files and directories are taking up on your hard drive.
Once it's installed (it is in most distributions' repositories) and launched, it shows you a brief view of all the different devices on your system. This can be a little confusing initially, because as well as showing the physical hard drive devices and other storage devices on your system, it shows you meta-filesystems like udev and the like.
Once you've got out of that first view and started a scan, however, things start to be a bit more meaningful and less confusing. You can click any of the devices on that first screen to scan them, so in this example, I click /dev/sda5 (my Linux root partition) and / is then scanned.
Each directory is shown as a segment of the ring, with directories closest to the root of the file system closer to the middle of the circle. In the screenshot above, the large orange segment near the centre is /home, for example.
Hovering over any segment shows you the directory it represents, its size and other information in a tooltip and also highlights its child directories with arrows to their segments. Click any segment to drill down into it and show its children in more detail if you need to.
It does seem a little confusing at first, but if you stick with it and get used to the way it operates, it actually is a very easy way to visualise your disk usage. After performing a scan, which takes some time as with all tools of this nature, it is easy to throw your mouse over the diagram and quickly work out what's using what.
Other than taking a little while to get used to and a slightly confusing start screen, Filelight is an equally useful tool for charting your disk usage graphically and is highly recommended for KDE users.