Disk usage treemap software for headless Linux
Solution 1:
NCurses Disk Usage (ncdu) is good for this. See http://dev.yorhel.nl/ncdu for details. It's available as a package for most popular distributions and lets you browse and find out where your disk space is used. It uses text characters to display a bar-chart of directory usage so you get a semi-graphical interface, in a text only environment.
Solution 2:
gt5 is very nice. It has a console interface and also creates html files you can view in your browser. It's in the repositories so you can just apt-get it.