I love this. Just reading the list make me happy.

I would contribute:

  xmlstarlet   Manipulate xml documents         http://xmlstar.sourceforge.net/
  jq           Manipulate json documents        https://stedolan.github.io/jq/
  screen       Terminal multiplexer (like tmux) https://www.gnu.org/software/screen/
  imagemagick  Manipulate images                https://www.imagemagick.org/
  ffmpeg       Manipulate video                 https://www.ffmpeg.org/
  gifski       Create high-quality gifs         https://gif.ski/

Oh I see I can make a pull request!