Word processing software. I remember my first job as a lowly admin assistant in the Civil Service where my job was to manage with the team's post, file lots of pieces of paper, and deal with the Divisional Typing Pool ruled by the fearsome and never-to-be-forgotten Mrs Kagan. Word processors not only changed the office organisation structure forever, it saved me from having to approach Mrs Kagan to ask for a letter to be retyped because my boss wanted to add a couple of words "just here, and here - today if possible ... please?".