After viewing this video clip from Ted.com (http://www.ted.com/talks/view/id/92), a few simple and general rules regarding presentations sprang to mind: Humor = Interest, and energy begets energy (in other words, make the audience feel involved).
The first rule applies to most presentations. Laughter, and by extention humor, is almost a universal language. If a presenter can make his audience laugh, then he's broken that proverbial ice. This allows the viewers to feel involved, opens them up to the information that follows, and makes the presentation much more enjoyable. There are, of course, times that this is difficult or inappropriate. A somber funeral may be a case of the latter, though I've seen enough eulogies artfully employ humor to lighten the mood to say that it is not always the case. A dry report of statistical facts may be an example of the former, though the Ted.com presentation certainly proves that humor may be employed if the venue is right.
The second rule, energy begets energy, simply means that it behooves the presenter to try to make the audience feel involved. Not only does this bypass the boredom that sitting through a lecture can cause, it also actsw to open the audience up to actively listening to the presentation rather than zoning out and "doldrumming" it.
A presentation that effectively and appropriately incorporates these techniques will almost always be more effective at imparting its point to the masses. By engaging the audience, audiences will retain more information, making the experience more successful for both the watchers and the speakers.