Oh, let's see, just a few:
-Book of Unremitting Horror (I do like me some monster manuals, doesn't matter the game. I have to say this has some of the best, and disturbing, creatures ever. A little modification, and it can really be adaptable to a number of settings. Jeez, there is some fucked up stuff in that book.)
-Horror Recognition Guide (More inspiration, and a great read. This has me wanting to play Hunter: The Vigil pretty badly.)
-Eclipse Phase(I really was going to get it anyway, but after hearing the actual plays on RPPR, I now have to own every Eclipse Phase book that will ever come out, like ever.)
-Night's Black Agents(I actually haven't got it yet, but I most definitely will.)
-Come to think of it, I'll probably pick up Shadows of Esteren at some point.
-The Laundry, both the RPG, and also The Atrocity Archives.
-Zombies of the World, Kindle edition.