Here is a quick tip to make your PowerPoint presentations a little more effective. If you setup Presenter View, you can see a great summary of your presentation on your laptop screen, and show the regular presentation on the projector screen.
So when I give a presentation, I see something like this.
You can see which slide you are on, speaker notes, slide number, the next slide, timing etc.
Anyway, it is very simply to setup, just goto the slideshow menu and activate Presenter View. Note that it will only be available when you have an external monitor connected.