Thanks to Carsten Knobloch a.k.a. Caschy, a german blogger, I found an interesting software. SpaceSniffer allows you to show how much disk space each application, down to each single file, uses the graphical way. It’s available for Windows 2000, XP, Vista and 7, and it’s freeware!
What it essentially does is, it scans the whole hard drive, renders different images depending on disk usage and assigns them to each single file and folder. There’s a way to show more details, meaning going deeper down to show the usage of each single file, or less details showing only the folders.
SpaceSniffer is more focused on clean graphical display than detailed information, like WinDirStat for example. You can directly manipulate the files/folders from inside the application. Double clicking a “block” will cause it to show you .
One use, suggested by Caschy, would be to delete unnecessary files if you plan to do backups. Saves time and disk space. I’m sure there are other uses for it, I personally use it to check usage by each application I have installed.