Every year Disneyland gives the Haunted Mansion a Nightmare Before Christmas makeover, putting Nightmare characters on top of the existing gags. I've never seen it, but this Youtube video gives me a pretty good idea of what it's about:
It makes you wonder- why hasn't Disney made a Nightmare ride a permanent part of the park?
Designer and Imagineer Christopher Merrit came up with a cool-looking concept for such a ride, (his designs are available to view here) and I can't see a damn thing wrong with his idea. The website The Neverland Files doesn't seem to know why it wasn't picked up either. C'mon, Disney, make it happen! Scores of black-clad teenagers are crying out (literally crying!) for this nightmare to become reality.