The Exorcist is probably the biggest Netflix release of the month (for now, at least), but Big Trouble in Little China, Wes Craven's New Nightmare, and Tales From the Darkside: The Movie are pretty impressive too. Extraterrestrial and Zombeavers are definitely worth watching as well.
We're curious to check out the Netflix Original Series, Between, which looks like a Post Apocalyptic Children of the Corn type of thing.
As far as Non-Horror releases go, Leon: The Professional, Payback, and Rush are all A+ efforts that are almost required viewing for anyone who likes great action dramas. Also, Longmire is a great show to binge watch, if you're in the mood for something that has a bit of a western sensibility about it.
It's not a huge list, and Netflix will no doubt be adding more titles that will be of interest us throughout the month, but for now, it's at least a good start.