I just found this amazing utility called
WinDirStat. Basically, you select a drive or directory on your computer, and it opens an explorer pane. The great thing, though, is that it also has a graphical component! In another pane, it shows every file on your computer as a colored rectangle. The larger the rectangle, the larger the file. Also, the rectangles are color-coded by file type, and there is an accompanying legend. The rectangles are grouped into larger rectangles of files in the same directory, which are then grouped into their containing directories, and so on. It really is a great way to find out how your hard drive is being used. Today, it helped me clear 25 GB of unused temporary and log files! I recommend this to everyone.
I also found another tool, called
HDGraph. It works in a very similar way, but it uses a pie-graph to show the proportional size of directories and sub-directories. It only shows directories, not individual files, and has no explorer pane, but it does show free space, which helps visualize how much of your hard drive is being used. I personally like WinDirStat better, but this is helpful when trying to find large folders.
Both of these are open-source projects hosted on Sourceforge.net. Both are deserving of an article on CyberNet. I urge everyone here to check them both out, and to list any other similar tools that they know of.