As a coach for speakers and presenters, I have learned a bit about what works, and why. Here is some of it:
The Impromptu Talk - An analysis of Mark Twain's speech, My First Appearance.
The Sales Talk - Steve analyzes the motivational speech from Shakespeare's Henry V, We Happy Few.
The Lecture - How give a good one.
How To Make A Toast - Be Appropriate. Be Interesting. Be Done. With examples for all occasions.
On The Importance of Listening - Even more important than good speaking. With anecdotes of non-listening.