Simon Whitechapel's
Kamp Kulture, about nazi exploitation movies which is a nice read tho i still think here in Italy we have one of the best source for this kind of cinema, and i mean Nocturno Cinema magazine (their dossiers and even books, which entirely focus on b-cinema and extreme cinema of every sort)
http://www.nocturno.it/default.aspxthen books like "Cinema Calibro 9" about gialli and police-movies, by Fabrizio Luperto
"Erosvastika" by the guys of Nocturno
"Joe D'Amato" by Gordiano Lupi and "Nocturno Dossier n.78 Joe D'Amato"
"Sex & Violence" by Roberto Curti and Tommaso La Selva (a huge book, from grindhouse/underground porno to Franco, Rollin, Lucifer Valentine, Fred Vogel...)
I will spare to you the enormous amount of books about Pasolini's work on Salò
It's a shame these books are not translated into english language
I'd surely like to read the long awaited and never published Jamie Gillis' book PURE FILTH (with a preface by Sotos), which really should be a fully sadean read about cinema, mostly focusing on the brilliant dialogues of Gillis' private movies- Feral House was supposed to release it but then nothing happened
Babylon Blue by David Flint, an other nice read about porn movies -much more entertaining than the lame The X Factory by Anthony Petkovich