Literature is a broad category for selecting ideas for an essay. For instance, discuss the Industrial Revolution's effect on humanity, as read in the poem "The Chimney Sweeper" in William Blake's book "Songs of Innocence and Experience." Or, comment on counter-literary movements by discussing Oscar Wilde's cry for a return to art in "The Decay of Lying: An Observation."
Any film of your choice is up for grabs as an essay topic. Pick your favorite movie and base your essay on the cinematic techniques used to invoke emotion, the element of time as a story-telling tool or even the themes and symbols seen throughout the film. Movies ripe for film critique include: "Inception," "Pulp Fiction," "The Departed" and "Memento."
History is the deepest well to pull ideas from. Choose a time period that interests you and narrow it down to a specific event. For example, write an essay discussing Martin Luther King Jr. within the civil rights movement; or discuss how Hitler's experience in The First World War helped him become a dictator in World War II.
Art can be discussed by both critiques of specific works or by movements of different styles. For this reason, there are many ways to go about critiquing artwork in an essay. For example, connect the work of British artist James Whistler to the literature of the Aesthetes, or discuss the contrasting dynamic between the Aesthetes and the Victorians.