The Fine Art of Murder : The Mystery Reader's Indispensable Companion (edited by Ed Gorman, Martin H. Greenberg, and Larry Segriff, with Jon L. Breen)

I did not finish this, although it is a wonderful resource for mystery fans. As it came out in 1993, however, it is very dated in its recommedations of subgenre titles. For an historical look at where the mystery came from and how it spread into its different perspectives, this is a great place to start research.