I use a command that'll play a good/bad sound effect based on previous shell command exit code.

Something like:

  function boop() {
      local last="$?"
      if [[ "$last" == '0' ]]; then
          sfx good
      else
          sfx bad
      fi
      $(exit "$last")
  }

I'd then do:

  $ make -j; boop

or

  $ nmap <...>; boop

That way I can focus my attention elsewhere while waiting for stuff that'll take anywhere from 20s-2min without losing track of time.

Lately I've been experimenting with throwing in notify-send in there too, but find it a bit much to both get sound and visual feedback.