I maintain the PowerPoint FAQ site at http://www.pptfaq.com and also develop the PPTools add-ins for PowerPoint (http://www.pptools.com).
In a previous life, I created slide (as in 35mm slide) presentations and ran a slide imaging (as in converting digital graphics to 35mm slides) service bureau. I also wrote for several magazines on PowerPoint, Lotus Freelance and Corel Draw topics.
And Before that, I was an advertising/commercial/industrial photographer and created multi-image presentations.