I have shortcuts to save last (sl) executed command and another to grep that file.

    alias sl='fc -ln -1 | sed "s/^\s*//" >> ~/.saved_commands.txt'
    alias slg='< ~/.saved_commands.txt grep'

You can also add a comment to the command before saving. For ex:

    $ foo_cmd args #this command does this awesome thing
    $ sl

I have a $HOME/bin folder full of bash scripts invoking imagemagick or ffmpeg one liners.

One handy idiom I like to use after typing out a long command that I might want to save is

    echo ‘!!’ > ~/bin/name-of-script

where !! is the previous command

care to share? :D

This one for instance to grab my desktop quickly without starting another program when I want to make a quick demo for a colleague:

  #!/bin/bash

  size=${1:-"1920x1080"}
  offset=${2:-"0,0"}
  name=${3:-"video"}

  ffmpeg -video_size $size -framerate 25 -f x11grab -i :0.0+$offset -c:v libx264 -crf 0 -preset ultrafast "$name.mkv"
  ffmpeg -i "$name.mkv" -movflags faststart -pix_fmt yuv420p "$name.mp4"