I'm behind on my blog reading (it's been one of those weeks) but I just found Scott's post of PowerPoint Advice. He couldn't be more right about not reading slides (and not just because he linked to me). This is a sure sign of a presenter who doesn't know the material. Back when I was explaining .NET to customers 3-5 times a week, I could do the presentation on a whiteboard while hanging upside down blindfolded
I actually try to avoid slides when possible and just explain everything with words and a whiteboard. The nice thing about this approach is that I can be flexible when the audience needs me to be. Today, I presented to a group of architects from an ISV on Metropolis and SOA. I had slides at the ready, but I spent most of the time just talking with the audience, not to them. When I finally did go to the slides, I found I had covered the vast majority of the information I wanted to explain and the slides were more of a hiderance than a help. I shut down the projector a few minutes later and went back to just talking.
Granted, for larger audiences (like TechEd), you need to use slides, but they should be a fall-back position when needed, not the first tool out of the toolbox. If you have to do slides, please follow Scott's advice.