Great post by Austin Kleon:
FOR SUCCESSFUL POWERPOINT PRESENTATIONS, LOOK TO CARTOONISTS by Austin Kleon: "Powerpoint (or Keynote) slide software solves the problem of presenting an audience with a narrative that demands both verbal and visual elements. A slide presentation succeeds when the visual display works with the verbal communication of the speaker to create a narrative in the audience’s mind. The juxtaposition of pictures and words conjure connections and meaning that pictures or words alone could not.
Some of the best uses of Powerpoint come from the masters of verbal/visual, picture/word communication: cartoonists."