Dark City: An amnesiac fights aliens at night with the help of an asthmatic psychologist.
Alternatively, in a city of narcoleptics, one man suffers from insomnia. A council of albinos move against him.
Dark Star: Incompetent hippies on a deep space demolition tour dispel their boredom by chasing and deflating a sentient beach ball. Over-confidently, they then enter a debate with a sentient thermo-stellar bomb.
Dark Water: Woman gets irritated when no one will fix her leaky ceiling.
Darkman: Doctor gets revenge on the mob using latex masks.
Darkness Falls: The Tooth Fairy is actually the ghost of a woman who was burned to death years ago in the town, and she murders everyone who sees her. But ... she cannot stand to be in the light - and so the protagonist (who saw her as a kid and survived) arms himself with a gym bag full of flashlights.
Death Note: Law student turns vigilante calligrapher with the help of a super-being who sustains himself on a diet of nothing but apples - avoiding detection by both his own father and a child genius who has a ludicrous appetite for carbohydrates.
Death Note: The Last Name: As before, but with the addition of two cute babes from a TV station and another cartoon super-being. Nearly everyone dies.
L: change the WorLd: A child genius who has a ludicrous appetite for carbohydrates with only 23 days left to live battles Eco-terrorists with a deadly virus.
Alternatively: A man commits suicide by notebook, adopts a kid and fights terrorists. ...In That Order.
Dogma: Two disgraced angels try to exploit a loophole in Catholicism to kill God and destroy the universe, and it's up to an abortion clinic worker, two stoners, a stripper, and the 13th Apostle to stop them. And there's a monster made out of crap.
Donnie Darko: An anti-social teenager sees visions of an anthropomorphic rabbit, has a jet engine crash into his room, and has one month to prevent the end of the world... which he is the cause of.
Doomsday: Scotland has been sealed off from the world to contain a zombie-creating virus epidemic. Ten years later a crack British commando team is sent in to investigate signs of life. Hilarity Ensues.
Dracula (1931): Two doctors and a solicitor from London must kill their neighbor because of his dental problems.
The Driller Killer: An artist goes stark raving mad and takes his anger out on his oppressors by way of a drill to the head.
Driving Miss Daisy: An old white lady and a slightly less old black man slowly become friends over 20 years as she tries to assert independence while he tries to do his job of driving her around. In the end, pie is had.
Drop Dead Fred: A woman with a cheating husband, a domineering mother, and serious self-esteem issues figures out how to solve all her problems with the help of her imaginary friend from childhood.
Duck Soup: Cheerfully insane dictator with a bizarre mustache starts a war with his neighbors, while an Italian and an Irishman spy on him.
Animal Crackers: Explorer with a bizarre mustache attempts to find stolen painting, while Italian and Irishman play music and attempt to hide it. Maybe.
A Day at the Races: An Italian and an Irishman get involved in horse racing so that a veterinarian with a bizarre mustache can take over a sanitarium for humans.
A Night at the Opera: Con artist with a bizarre mustache attempts to make money off of Il Trovatore, while Italian and Irishman play music and attempt to help the career of a tenor. The most famous scene has all of them, including the tenor, in a small room.
Dude, Where's My Car?: Two guys with amnesia eat pudding and play with a Rubik's Cube. Out-of-towners try to seduce and/or mug them.