Ice Age 3: Dawn of the Dinosaurs: One of the mammals discovers fatherhood. An attempt of another to do the same leads him to need rescue. The unlucky guy meets the woman of his dreams... and leaves her behind for food.
Idiocracy: Blood Sports are used as punishments, and humans nearly go extinct from incompetence, famine and drought. It's a comedy.
Igor: A mad scientist's assistant invents something revolutionary, with the help of an immortal suicidal rabbit and a brain in a jar. His plans backfire when his invention does not turn out evil, and instead aspires to be Annie.
Or, Quentin Tarantino teams up with Eli Roth, Brad Pitt, and the Jewish kid from Freaks and Geeks. Their mission is to stab history in the face. With a baseball bat.
Ink: A ragtag bunch of invisible, stylish, physically fit, attractive dead people try to get a young girl to wake up after she is kidnapped by an albino with a gigantic schnoz. This can only be done if her dad stops being a Jerk Ass.
Or: Two girls get lost in a pile of marbles and try to take the train home. With the help of a hobo, they go through a torture chamber, hijack a movie studio, and unleash a monster from the dungeons. It's actually a Tear Jerker.
Or: Girl deals badly with moving, decides to get away on bus, and still gets off it.
Or: The stress from moving to a new town causes a young girl to lose her marbles.
Interstellar: Astronauts embark on a decades-long quest into deep space to find a way to save humanity from extinction, but it turns out all they needed was a broken watch.
Insomnia: A cop who doesn't get enough sleep bungles his way through a murder mystery in some backwater town. It's not a comedy.
Interview with the Vampire: A dysfunctional family consists of an effete Parisian socialite, an emo former slaveowner, and an increasingly bitter "child" who kill for fun and profit. Later, two of them conflict with a theatrical group.
Queen of the Damned: A French violinist forms a rock band, pisses off all of his old friends, and gets kidnapped by an Egyptian nymphomaniac.
Alternatively: A lonely man finds a woman and child for life.
I, Robot: A detective, while investigating a death in a corporate building, learns that the company's new product line is defective.
I, Robot Alternatively: A bigoted, superstitious cop, isolated from his peers and on the verge of losing his badge, meets an attractive but socially-awkward scientist of a different race. While spending the entire movie getting hot-and-bothered from each other's mere presence, they meet a Messiah figure patterned after Martin Luther King Jr. who is scheduled to die by lethal injection, and end up taking on a villain who is a product of the excesses of corporate America. Surprisingly, not overtly political. Features a cameo by Shia Labeouf and voice acting by Alan Tudyk of Firefly fame.
Or: Two children discuss the value of peace and life. Then, bigger one responds by shooting at the United States military and taking a nuclear missile to the face and being blown apart, then recovering.
Or: Someone else's hunting trip makes someone uneasy. In the climax they respond by taking a nuclear missile to the face.
Iron Man: Terrorists put an engineer in a cave with a box of spare parts. This leads the man to solve unethical business practices of his company.
OR: A rich guy goes to Asia to drink and flirt, gets a new suit, and leaves with a new enlightened outlook on life.
OR: Rich drunk with a heart condition builds flying hot-rod, races larger hot-rod.