Why it's called "Book of Shadows"
People endlessly complain that there's (supposedly) no Book of Shadows in the movie, but it’s simply not true. The main character Jeff is a movie enthusiast with ambitions of being a filmmaker and "Book of Shadows" is the name of one of the scripts he put together and intends to shoot. So it's not something totally out of nowhere that Artisan dubiously added to the title, as many people suggest. Yes, the studio added it, but it had relevance to the movie. Furthermore, the actual 'Book of Shadows’ is a Wiccan spell book and is figuratively used in the movie in that the group obviously falls under the spell of the Blair Witch after entering her diabolical terrain.
My 150 (or so) favorite movies:
http://www.imdb.com/list/ls070122364/