I'm interested in finding suggestions for sources who write about exploring traditional mythologies and their relevance to modern times. This would be a book that contains analysis, interpretation, and narratives applying classical myths to understanding modern issues, psychologies and cultures. It could be specific to a particular mythology or encompassing several traditions.
If you are looking for a blend of wide ranging mythology set in a modern context, Neil Gaiman's American Gods is a solid place to start. He's done a bit of writing on myth generally, and this blends things nicely into social commentary and just (in my opinion) a stellar story. It's fiction, but it's well worth checking out.
The closest thing to what you are asking that comes to mind is Old Norse Religion in Long-Term Perspectives: Origins, Changes & Interactions (I'm including the Google Books link because there you can find the ebook for a rather cheap price). It's a collection of papers by some of the leading scholars in the field of pre-Christian Norse religion. The fifth section of the book, "Reception and Present-Day Use" should be up your alley.
Several of the papers contained therein deal with the relationship of old Norse mythology with modern day political and religious movements, and its role in nowadays social and economic framework. I definitely recommend you take a look at it.