The Danse Macabre opens a wide vista of options for Vampire and to a lesser extent other World of Darkness games. If you wish to expand your campaign in any of a variety of directions, this book is full of useful tools and inspiration to do so.
The Danse Macabre is a 266-page PDF (260-pages if you remove the covers and ads) for Vampire: the Requiem (and the World of Darkness in general) RPG written by Russell Bailey, Benjamin Baugh, David Brookshaw, Christopher Cowger, Bethany Culp, Matthew McFarland, Greg Stolze, and Chuck Wendig and published by White Wolf Publishing.
Sea of Stars RPG Design Journal 