SpaceMonger is a tool for keeping track of the free space on your computer. Each file or folder on a given drive is displayed in a box in the main window whose size indicates the space it takes up (in relative comparison to all the other files in your system). So, for example, if the “Windows” box takes up 90% of the screen, the “C:Windows” folder and all its sub-folders and files are taking up 90% of your “C:” drive.