BleachBit deletes unnecessary files to free valuable disk space, maintain privacy, and remove junk.
A disk usage analyzer with an ncurses interface, aimed to be run on a remote server where you don't have an entire graphical setup, but have to do with a simple SSH connection. ncdu aims to be fast, simple and easy to use, and should be able to run in any minimal POSIX-like...
feh is an X11 image viewer aimed mostly at console users. Unlike most other viewers, it does not have a fancy GUI, but simply displays images. It is controlled via commandline arguments and configurable key/mouse actions.
Vim inspired text editor with support for multiple selections and scores of other "out of the box" features.
od is a command on various operating systems for displaying ("dumping") data in various human-readable output formats. The name is an acronym for "octal dump" since it defaults to printing in the octal data format.