Wonderland turned me on to the Flash site for the movie The Grudge. Most Flash promo sites suck, frankly, but this one manages to capture some of the creepy ambiance of the movie, letting you explore the haunted house from the movie.
The best part, though, is when the house finally gets you. The site says "The Curse has claimed another victim," and it starts fading in the names of other players who have also lost in the game. A clever twist, connecting the game itself to the other players it has apparently taken as its victims. Very cool, and very much in line with the all-consuming theme of the movie. Well done.