Abomination Vaults
These are supplements and additions to the Abomination Vaults adventure path, published by Paizo, Inc.
A collection of side quests for the heroes during their adventure.
An Alternate End Villain [spoilers, obviously]
The end boss of the adventure path has been pretty widely spoiled in the popular gaming media, so this alternate boss can be used to add some unexpected twists and connections to other parts of the world. It sets up the possibility for the players to face off against high level undead forces after the adventure path.