This should help with speech topics and the extra credit option...
If you are searching for a topic, why not take a cue from others? Or if you are not sure how public speaking works, why not watch a few speeches?
My students receive extra credit for evaluating and studying speeches. All students learn from watching others. Here are sources to use for links. See the right hand column of this blog for additional links and ideas.
CSPAN has an archived of video, audio and transcripts of State of the Union Addresses. http://www.c-span.org/Executive/State-of-the-Union.aspx