An important independent organization that "provides information on the issues, attitudes and trends shaping America and the world," through opinion polling and social science research. Very useful for media-related speeches.
This freely available online resource, as of March 2018, has nearly 1600 entries online. From its inception, the SEP was designed so that each entry is maintained and kept up-to-date by an expert or group of experts in the field.
A great spot to find a wide range of talks. Use the filters, to narrow by topic, duration, speaker, or subject. The "sort by" dropdown allows you to narrow by type of talk. Take a listen!