Discus is a GPL text-mode disk space usage program I wrote in 2000 (and haven't updated since). It still works in Linux, and it should work in other UN·Xes where Python's statvfs module or the stat program is available. If it works on your OS, please let me know.
Discus aims to make df(1) prettier. Features include color, bar graphs, and smart formatting of numbers (automatically choosing the most suitable size from kilobytes, megabytes, gigabytes, or terabytes). Or choose your own size, along with specifying the number of decimal places you'd like to see.
A screenshot with the default settings:
A screenshot with -m (megabyte) and -p 0 ( no decimal places) options:
The latest version is 0.2.9 (view changelog). A Debian 3.0+ package is available, thanks to Ron Farrer, and a Debian 2.2 package, along with a .tar.gz package. Both contain the Python source code within the discus executable.
P.S. I chose the name Discus because it resembles “disk use.”