Is there any software for visual display of disk space?

My personal favorite is GNOME Disk Usage Analyzer (baobab):

You can install it with

sudo apt-get install baobab

Select any file from the table on the left side to move it to trash on right click.

There is a fully rewritten version of KDirStat, by the same author, named QDirStat. Fast, customizable, using Qt5, desktop-agnostic (not depending on KDE components), and showing a squared view rather than concentric circles, which I personally find clearer. There is a ppa available for the installation.

Personally I like KDirStat

you can install with

sudo apt-get install kdirstat