Being a keen reader of Garr Reynold's Presentation Zen blog, I had no choice but to follow his recommendation for taking a look at Al Gore's presentation on global warming on Google Video (Gore begins around 9:30 into the video). After watching the whole presentation, I can only repeat Garr's words:

See this film and you get to see a well designed and delivered presentation sans bullet points, and you may just learn a thing or two about how to save the planet as well. What could be more important?

Indeed, a passionate talk on an important topic and delivered well.