Tim Wilson has a useful set of suggestions on how to close a speech. One of my favourites, that he doesn’t mention, is to leave with a challenging thought. It could be a question, but doesn’t have to be. It should produce “an ah-ha moment” or a smile from the audience, of understanding and agreement.
Your conclusion should do much more than simply tell your listeners that your presentation is over. Your entire presentation, in fact, can hinge on the final impression you make. It’s that last impression that can linger the longest. So preparing a strong ending to your presentation is every bit as important as preparing a strong opening.