My own Running, Cited Portmanteaux List. Not quite a rhetorical figure, I realize, but related (and fun).
American Rhetoric. Love this site. An encyclopedic collection of not only rhetorical sources, but also multi-media sources, including when possible video and/or audio of speeches and rhetorical figures.
Literary Terms.net. Just found this and haven’t poked around a bit but seems to have a lot of good examples from a range of (categorized) sources and media: pop culture, literature, etc.