This site contains a database of and index to 5000+ full text, audio and video versions of public speeches, sermons, legal proceedings, lectures, debates, interviews, other recorded media events, and a declaration or two. You can search for a specific speech or check out the 100 Top Speeches.
Toastmasters International is a non-profit educational organization that teaches public speaking and leadership skills through a worldwide network of meeting locations. This link will take you to Tips for Public Speaking. There are also additional links to explore on this page.