Watch "One Missed Call".
Bored last night while the rest of the clan was out of town for my niece's birthday, I queued this up on the On Demand, not expecting much. And sure enough, for the first 10 or 15 minutes, this seemed to be not much different from the Ring or Grudge or any number of other Japanese horror flicks. But then it got...scary. And real, real tense.
You know that manic laughter you get on a particularly startling roller coaster? Yeah, that was me. I'm sure the neighbor thinks I'm insane now, assuming he had any doubts before. Not to mention said neighbor (whose driveway is right outside my living-room window) slammed his car door at one quiet point in the movie, causing me to jump, catlike, into the air several feet.
This is directed by Takashi Miike, by the way, who I understand is considered to be sort of a Japanese Quentin Tarentino. I remember watching his film "Audition" some years back and finding it a bit... disturbing.
I suppose it helps to be in a hundred-year-old house, all alone, in one of the most haunted cities in the US, but this flick rated really high on the creep-o-meter. See it if you get a chance. Apparently there's an American remake of this, but I'd be surprised if it's as good (even the movie-poster art looks a bit goofy).