Back in 2005 I taught a class where I gave an overview of various parts of the .NET universe (at the time, the WinFX universe). I covered everything from C# to data binding to ASP.NET to service-oriented architecture to web standards. My goal was to give a familiarization with each of the topics so that the students can then learn the topics on their own in a way that best fits them.
My first session, however, was a presentation experiment. Instead of using really nasty verbose slides, I had just a few words on a slide and on one slide I had simply the number 42. Don Box would have loved my presentation. The point of the experiment was to make sure that people were paying attention to the topic and not simply reading a useless slide. I really think that PowerPoint is a massive hindrance to education. You can access my experimental presentation, named .NET Overview, below.
My next to last session was on web standards and in this session I simply told a story and then gave a few examples showing how web standards development is the only web development that is acceptable. You can access this presentation, named Web Standards Presentation, below.
Below is also a link to a video where Don Box talks about giving great technical presentations. I would recommend this video to anyone who gives talks on really any topic. Don't just watch it, study it. It takes practice.