As a lecturer, I have given tons of lectures. As a researcher, I have also given quite a number of presentation in seminars and conferences as a speaker or keynote speaker. However, after almost 16 years, I still feel that there's more room for improvement. I'm still honing my presentation skill. There are a few books available on using PowerPoint to deliver good and engaging presentation. Here's one: Why Most PowerPoint Presentation Sucks by Rick Altman. The following presentation from Slideshare gives some useful tips on the art of preparing good presentation.