Presenting the ideas you develop to a big audience in most cases is a pain. Most of the time the layouts you make (unless they are screen-designs) don't feel right, you cannot go through the pages of a folder for example. Therefore is even more important that you engage your audience. Same thing for powerpoint presentation you get to pimp. The most of time are just plain awfull. The following book gives you in an easy and understandable language the basics on how to structure presentations, not just powerpoint. It's caled "PresentationZen" by Garr Reynolds and a foreword from Guy Kawasaki. Don't get fooled by the title - it's nothing esoteric. It helps you bring your audience to go out of the presentation wanting for more. It also helps you to guide the authors of the powerpoints, if you are just the one who overhauls them, to get you better material to work beforehand.
I use this approach with quite some success, by getting into the process of structuring a presentation right when the authors has his material togheter. This is even before they make their manuscript. Try it - it's just a few bucks investet in the right place.