To clarify - this is a tool meant for understanding your audience and structuring your story before designing any supporting visuals. I have found that when you have the story ironed out, any supporting visuals are much easier to create.
I teach a presentation design class at a business school and have developed a tool called the Lean Presenter's Canvas. It is v0.1 (literally released this week) and is based off years of teaching this MBA class as well as working with business professionals on their presentations. It is intended to be a guide to map out a presentation in one page before spending too much time in slideware.
We'll post revisions based on usage and feedback as well as offering more tools to help craft and design a presentation (all licensed under Creative Commons).
Since we're following a lean approach - feedback is welcome!