Films On Demand: search for "public speaking" and under Filter Options, All Subjects, choose Communication. These results may vary from the collections linked below. See also:
Pew Research Center, a nonpartisan fact tank that informs the public about the issues, attitudes and trends shaping the world, useful for researching topics.
Roper Center for Public Opinion Research at Cornell University, provides over 50 years of public opinion survey results, including opinion polls on important social issues.
TED: Ideas worth spreading: “Riveting talks by remarkable people,” offers video of talks on numerous topics, searchable by theme, speaker, etc. Suggested for examples of various speaking styles.
