The EMSEduCast is the podcast by and for EMS educators. We have discussed PowerPoint, Slide Design, and Presentation tips on several episodes:
PowerPoint Best Practices for EMS Educators: Episode 25
Lights, Camera, Action: Episode 62
Visual Broccoli for Presentations: Episode 127
Gold Medal Presentations: Episode 142
I also recently posted about Effective PowerPoint Slide Design.
Finally, you can see how I put some of these concepts to work in my PowerPoint presentations posted on Slide Share.