JFolderGraph is a tool written in Java that allows users to scan their hard drive for large folders. The gathered information about your system folders will be displayed in a pie chart (circle graph) sorted by size.
JFolderGraph will be very useful especially when you run out of disk space and don't know which folder you need to delete first. This tool is written in Java, so you need to install at least Java 6 or higher to be able to run this tool. To install JFolderGraph under Ubuntu 11.10/12.04, run the following commands from the terminal:
sudo add-apt-repository ppa:upubuntu-com/apps
sudo apt-get update
sudo apt-get install jfoldergraph
The tool can be then started from the Unity Dash:
JFolderGraph' home page is here.