Seth Godin recently made the provocative suggestion that you break up your typical presentation into 200 slides. He's talking here about a Ballroom style presentation, not the kind of thing you'd present to physicians, scientists, marketers, managers, prospects, board members, or any other small group that you are trying to persuade to take a specific action.
But for presenting to a large group, such as a sales convention, nothing beats a good Ballroom style presentation. Here's one of my favorites, Dick Hardt's now legendary OSCON 2005 presentation:
(If you can't see the video, click here.)