The Innkeepers is about a haunted hotel, and it was shot at the hotel West and his Crew stayed at while filming The House of the Devil. From the AV Club interview:
When we made House Of The Devil, we lived in this hotel [The Yankee Pedlar in Torrington, Connecticut]. And we made this satanic movie out in the middle of nowhere, but weird stuff would happen at the hotel. The whole town was obsessed with it being haunted; the people that worked there were obsessed with it being haunted. Cast and crew started believing it was haunted. So I wrote a movie about the experiences we had making that movie. That’s really where the inspiration came from.
At the end of the viewing I attended there was a brief Q&A. A couple people asked smart, technical film questions about lenses and stuff. I was a little confused by the film's ambiguous ending, so I looked like a big dummy by essentially asking, "Did the movie end the way I thought it ended?!" And they said, "Sorry, we refuse to answer that question." Then someone asked another question about lenses, and I accidentally swallowed my chewing gum.
The Innkeepers is showing right now at the Ritz at the Bourse, so if you live in Philly you should check it out. It's creepy. And funny.