Danny Mass, in his blog, TILT – Teachers Improving Learning with Technology, offers some fascinating ways to create Flash-like animation in PowerPoint.
First, he reviews PowerPoint’s general custom animation feature. Then he discusses:
“Keyframe” animation with duplicate slides or sprites. For example, you can make a stick figure appear to move its arm, or to walk. Sprites are existing figures that you can download that appear in various stages of motion.
Flash once animation, which can give the appearance of keyframe animation. Danny uses a spider darting around the slide.
See his video explaining the techniques. You can download his PowerPoint file in the same place.