Some times reference sources are good places to get an overview or grounding in a topic.
Also check out Topic Pages in Credo Reference--these can be helpful to get differing perspectives on a topic.
Encyclopedia of Rhetoric by 
Rhetoric and Society by I'm putting some books here that might be useful in terms of figuring out the rhetoric or discourse around some topics. I'd also like to suggest that you try looking into the book series we have that address topics in a debate or argument format--some of these series are:
These books can help you find a topic, or explore the variety of rhetorical discourse around a topic.
Dialogue and Rhetoric by 