The book that most closely resembles this paradigm for me was Mathematics in a Postmodern Age: A Christian Perspective - the book is about exactly what I thought it would be about, and it's written for exactly the audience I thought it would be. That topic and audience are both exceptionally small; nevertheless, the book serves its purpose admirably.
My challenge to you is this: tell me about a book that is probably not of interest to more than a few thousand people in the world. If it's a good book, so much the better.
