Whether you want a chapter-by-chapter synopsis of any of the Brontës' novels, biographical notes, descriptions of their schools or even the names of their pets you'll find it in this comprehensive book.
Fun if you are a Brontephile (and I've got the coffee mug to prove it!), this book has over 500 entries on Bronte trivia. Some articles are more interesting than others--I love the stories about how close Anne and Emily were, how close Charlotte and her father were, and about Haworth and its environs (specifically, how they inspired the geography of Wuthering Heights.) Other entries, like the one on Heathcliff of all people, were surprisingly dry.
This would make great reference material for anyone doing a paper on either the Brontes or their works. Included are highly detailed synopses of all of their novels.
I'm going to continue searching for a prose book about the lives of the Brontes.