All headlines should be complete sentences (ending with a . ! or ?)
Horizontal logic: All headlines should read together like a story, in order. If you just read all the headlines on each slide, without reading the bottom stuff, you should be able to learn the main messages of the presentation.
Vertical logic: All content on the body of slides should directly support the headline sentence. Further, each slide should stand on its own - and be understandable, outside the context of the rest of the deck. When taken in context however, it should strengthen the presentation of the story
Genome Biology article published on PubMed: Powerless to stop myself
Edward Tufte, extracted from his The Cognitive Style of Power, on NASA, Shuttle Columbia, and Powerpoint: PowerPoint Does Rocket Science--and Better Techniques for Technical Reports