I use a rating system similar to the grading systems used in schools. Instead of A+, A, A-, B+, etc., I assign numbers. I feel it allows for better delineation and scoring rather than a 5 point scale. I measure things in my job using this type of system and it makes more sense to me. These numbers more accurately represent how I feel about a book.
All kinds of books, Fiction, Historical Fiction, Romance, Mystery, Suspense, Thriller, with the occasional Classic thrown in for good measure. UPDATE: This reviewer website is no longer maintained or updated.