Browsers provide data entry windows with strict word limits. Try to squeeze in some extra ones and you are informed that you have minus x characters left.
Today’s invention is to apply this to PowerPoint presentations.
Too often have I received (and given) talks in which there were way too many words on a slide. This embedded tool would constantly check the word count and object if it was about to be exceeded.
It might also provide guidance as to the minimum feasible fontsize for legibility (perhaps you could supply the size of the auditorium and this font limit would be automatically adjusted).