I've already mentioned how much I enjoyed Nancy Duarte's book slide*ology. Here's an easy but impressive PowerPoint technique from her book that I have used to great effect: the Push Left transition. (Click here to view.)
This works particularly well on a series of slides with mostly images and minimal type. Let's say you have 3 slides in the series. On Slide 1, insert two images. The second image should overlap the right edge of the screen. Then take that image and cut it into 2 separate images using Photoshop or another image editor. The first image stays positioned on the right edge of Slide 1, the second image is positioned to the far left of Slide 2.
