I maintain the PowerPoint FAQ site at http://www.pptfaq.com and also develop the PPTools add-ins for PowerPoint (http://www.pptools.com).
Prior to that, I created slide (as in 35mm slide) presentations and ran a slide imaging service bureau. I also wrote for several magazines on PowerPoint, Lotus Freelance and Corel Draw topics.
Q&A for professional and enthusiast programmers
Q&A for computer enthusiasts and power users