There are so many bad ways to use PowerPoint (or Keynote if you own a Mac) when you deliver a presentation. Again, let's cut to the chase — here are my 5 Must Do's when it comes to delivering a presentation:

Know Your Material Feel free to glance up and see what slide you are on, but don't read the slide verbatim (the only caveat to this rule are quotations). The act of glancing at the slide allows your audience to follow your gaze to the slide, get the gist of the image/message, and then re-focus on you. These actions develop a great synergy between the presenter and the audience.
No Lecterns or Pedestals You need to reach out and touch your audience. Placing lecterns, tables, and stages between you and the audience separates you from them. You need to step out into the audience, get to their level, and move around. That will make your presentation much more powerful.
Act Naturally Animate yourself. Too many presenters try to act too cool. Move your hands, smile, raise your voice - presenting is ACTING. And the audience wants a performance. Make a powerful point.
Greet Attendees Prior To The Presentation Arrive really early - 1-2 hours and setup your entire presentation, LCD projector, laptop and make sure they work flawlessly. Then when the attendees arrive, mingle with them. Introduce yourself, learn their name, and learn a little about them. This is a trick I use to then incorporate their experiences into my presentation: "Take Tom from Tacoma, he's a used car salesman with a speech impediment . . ."
Pay Attention To Your Audience Regularly temperature check for attentiveness. If you begin seeing yawns, pick it up a bit - start calling names for examples. Get the room moving - constantly ask for questions - I ask "How am I doing so far? Have I lost anyone yet?" Your delivery should moderate to the audience - pick it up or slow it down.

As I said in my last post, my comments might sound harsh - but I am a highly discriminating audience. There are too many bad presenters (90% awful to 10% great) - so take these tips to heart and you will be one of the 10%. Good luck!

P.S. Again, feel free to agree or disagree with me (that's what the comments section is for) - I look forward to the discussion!