There's
Baobab (Gnome Disk Usage Anaylzer). It's available through Synaptic. I looked at the dependencies (per Debian) and even though it is a Gnome app it didn't appear to require half of the Gnome Shell, so it might be worth a look.
There's also cdu (color du) which is a Perl script that runs the bash "du" command then "colorizes" the output and creates some nice bar graphs (but not pie charts) of the usage output.