Sometimes looking at other people's speeches will help you come up with a topic and give you an idea of "best practices" for public speaking. You can also use famous speeches (such as FDR's fireside chats, linked below) as audio/visual aids in your own speeches.
Academic LexisNexis is a comprehensive, multi-disciplinary database that is known for its up-to-date news and information. For current event speeches, use the News search. Under the "Search by Content Type" menu, the Biographical Information search is also excellent for finding biographical information for biographical or tribute speeches. Access LexisNexis Academic at the link below.