Them is a French thriller/psychological horror movie released in 2006. A schoolteacher and her writer husband live in a country house in Romania. One evening, they receive a strange phone call, their car is stolen, and then they are menaced by intruders. Yes, we've seen this formula a million times. Someone breaks into your house and makes your life hell. But this movie was amazingly creepy.
It's shot pretty much in real time, once the action gets cooking, and has a realistic almost documentary feel to it. That docudrama thing can work for or against a movie, but here it really works. I think the fact that it was in French made it all the more eerie for some reason. The acting is quite good, and both the opening and closing sequences are surprising and chilling.
The movie I would compare it to sytlistically is The Texas Chainsaw Massacre. It doesn't have the same sweaty unpleasantness as Chainsaw, but it shares that shock and subversion.
Now I need to go lock my front door. . .