Ouija Board

A Ouija (pronounced "weejah" or "Weegee") board has letters, numbers, and a few short words written on it, with a pointer called a planchette perched on top of it. Someone (often more than one person)touches a pointer and asks a question of the board. The pointer then may start to move, apparently on its own, and hopefully provide an answer.

The belief is often that it will move by itself seemingly without anyone moving it, meaning that something else is moving it, often someone from the afterlife, or someone with one hand under the table and a magnet, or someone a bit away with a remote control. It's usually one of those three. Unless magic and psychic powers are rampant in the series, someone will be accused of moving it themselves, and they will of course insist that they're not.

Anime and Manga

The Destiny Board from Yu-Gi-Oh!.
In Shaman King, Tamao uses a variant of this to perform divinations, in her initial appearance she is presented as being so shy as to be using it for regular comunnications as well.
The girls in Noein use one to try to figure out what's bothering Haruka (who is being hunted by people from Another Dimension). It spells out the name of the Big Bad: Noein, although at the time none of them knew what that meant.

Film

In Paranormal Activity, Micah and Katie try to use an Ouija board to talk with a spirit, despite warnings of the dangers from their hired psychic help. At one point, the Ouija board even catches on fire.
An Ouija Board wakes the evil djinn in Long Time Dead.
In Witchboard, the use of a Ouija board allows an evil spirit to enter our world and start committing murders.
In Drive-Thru, the villain communicates hints to his next murder victims through a Ouija board, a Magic 8-Ball, and an Etch A Sketch.
Jason Quincy (Howie Mandell) uses what is called the Tabarrok Board in the Apocalypse film series movie Tribulation in order to find out some things. Two of the answers he gets from it are Genesis 11:6 and "I AM".

Literature

Planchette automatic writing is discussed in The Haunting of Hill House. Mrs. Montegue and her assistant try to use it to contact the spirits of the house, which disgusts Dr. Montague, who approaches things from a more scientific angle.
In Diana Wynne Jones' The Time of the Ghost, the titular ghost tries to send a message to her still-living sisters via an Ouija board they are playing with (though it doesn't go as well as she had hoped because she's not very good at manipulating physical objects yet).
In The Stand, a Ouija board informs Nadine that she's supposed to be Randall Flagg's bride. Later, she uses one to contact him.
Caroline in The Bailey Game owns one, and at one point she tries to use it to communicate with the ghost of a supposedly dead boy, Michael Bailey.
In Victor Pelevin's Generation P, Tatarsky uses one to summon the ghost of Che Guevara and asks him for insight into advertising and marketing.
Ephraim Kishon once met some people too interested in the occult. Since nothing happened when he joined the session, he gave the glass a little push by himself. The "spirit" they contacted introduced himself as "MR 4K?LLL", which the head spiritist interpreted as a spy's code name. Later, they contacted Aaron (Moses' brother) and asked him for his favorite Jews. The answer: "David... Judah Maccabee... Ben Gurion... Ephraim Kishon..." But is it his fault that Aaron likes reading good satires?

Live Action TV

In a Monty Python's Flying Circus sketch about police taking up occult methods, four policemen are shown using a Ouija board, with unhelpful results:

"Up yours? What a rude Ouija board!"

In Charmed, the Halliwell sisters are in possession of an old Ouija board, and are sometimes contacted by their mother, grandmother and other higher beings through it.
In My Babysitter's a Vampire improper use of the family's antique Ouja board ends up releasing a demon that promptly possesses Sarah.
In Kyle XY, the group tries to use one to figure out Kyle's Mysterious Past. It spells "781227", Kyle's "production number" at the facility he was created.
In episode 2.1 ofSupernatural, Sam uses one to communicate with Dean, who isn't particularly impressed with this strategy.

Dean: "I feel like I'm at a slumber party."

Video Games

In The World Ends With You there exists in-game a variation called Reaper Creeper, it's a paper with three symbols inscribed on it, arranged in a triangle with a circle around them, each has a different colour, White, Black and Red, a ten yen coin is placed on the paper and allowed to move by itself in order to provide answers to the one using it. The coin is moving by the players influence.
In Banjo-Kazooie, the player rides on a sliding glass over a series of letters in the same manner as an Ouija board to spell a word in order to get a Jiggie.

Newspaper Comics

Calvin and Hobbes had a three-strip sequence in which Calvin and Hobbes play with a Ouija board. The first question asks, "Who is smarter, Calvin or Hobbes?", led to a tug of war. Calvin then asks the board if he will grow up to be president, and it produces the answer G-O-D-F-O-R-B-I-D. Finally, they ask the board how it knows all the answers to life's mysteries; the board answers "3."
On April 1, 2005, FoxTrot, Get Fuzzy, and Pearls Before Swine did very similar strips involving Ouija boards being used by Bucky/Jason/Rat to justify hitting Satchel/Paige/Pig.

Theatre

In The Bat, Cornelia asks a Ouija board if her hysterical maid Lizzie is right about the Old Dark House where they are staying being haunted. The Ouija writes wildly, but the first intelligible string of letters spells "B-A-T."

Web Comics

Eerie Cuties Chapter 9: Uninvited. As we can see, our excitable young vampire drafted her fairy and ifrita part-time minions to contact their succubus friend who they assume currently is being bored in hell (she isn't, by the way) to find out details on how to sneak her back. What Could Possibly Go Wrong? It's not like the title sounds ominous, or something.

Web Original

The catalyst for Slendy and other such demons showing up in The Dead Are Watching.

Western Animation

One episode of So Weird featured a Ouija board that warned Annie of danger.