There are a lot of examples of great presentations out there, but few are better than Randy Pausch's "Really Achieving Your Childhood Dreams." It's over an hour long, but it's worth every minute of your time.
And it's also worth visiting the Six Minutes blog for an analysis of what Pausch does well, and how you can adopt those skills the next time you make a presentation. There's no better lesson in the power of connecting with your audience.
Bonus coverage: watch Pausch with Diane Sawyer on ABC, April 9 at 10 p.m.