J.K. Rowling's Plot Spreadsheets

The author and mastermind of the whole Harry Potter universe uses plain old notebook paper and a ballpoint pen to develop the intricate plot structures of her books. Down the y-axis, she lists chapter numbers and a month-based chronology, and along the x-axis she lists various attributes of each chapter like title, events and even prophesies integral to each segment of the book.

I think this is fascinating and I'm so curious to know what other authors use similar, low-fidelity planning methods. Also, it goes to show that even in a multimedia age, most good ideas start with a pen and paper. More about the spreadsheets here.