In many presentations, there's one key image or message which you want people to remember. You can ensure that slide has maximum impact by ensuring that the ones either side of it are less interesting.
Picture from Slideshare
Microsoft blogger Joy Miller notes in a round-up of tips from the 2011 Presentation Summit that this approach, while seeming counter-intuitive, is often recommended by experts:
For a key slide to stand out, it must have weaker neighbors; less impactful slides before and after.
That's not to say you should deliberately put super-dull slides into a presentation -- nothing kills like tedium. But it makes sense, for example, not to put an amusing video clip right next to your key message. Video is a great way to break up a long presentation, but you need to think carefully about structure. For more ideas, check our list of tips for presentations that don't suck.
Make the world a better place one presentation at a time [PowerPoint Blog]