Script Fic

Naturally, writing a Fanfic in the form of a script. Originated as a way of giving a sense of illusionary "officialness" to a fic for a TV series or movie (Look! It can be filmed as-is!), which makes the format particularly popular for continuation fics, and/or to use narrative tricks that wouldn't sound right in prose. It also functions as a prime outlet for writers unskilled at detailed description, and who despise Wall of Text, but talented with dialogue. Most MSTings are written in this format as well.

In addition to screenplay-type script fics, there are also those that are simply a script, without the technical terminology to describe the "filming" such as "pan", "exterior and interior", etcetera. (Which means they aren't scripts at all, of course.) Some call this variant "chat fic".

Though some readers think the lack of prose detracts from the story, others like the enhanced focus on the dialogue and action. A good script fic can accurately describe what is going on in the story without using prose, which is part of the challenge (to be coherent without using narrative and relying on action and dialogue to carry the story and explain what is occurring). It can be an interesting challenge writers who want to practice writing dialogue and experiment with form.

Occasionally enough stories are made that they're accepted as so-called virtual seasons.

Famously, Fanfiction.net banned script-formatted fics (along with chat fics) in 2004, creating a chain effect that effectively decreased their popularity; most of the most notorious examples of script fic below were written before the ban or are archived in different sites.

Anime and Manga

 * Narrabundah 1/2, Urac Sigma's mid-1990s re-creation/reimagining of Ranma ½, is a prime example of script format taking a good fic idea and making it hard to read and enjoy. In general, the Ranma fanfic community had completely abandoned script format by the late 1990s.
 * On the other hand, a well-done script-format fic was, for a short time in the mid-late 1990s, successfully passed off as a pirated copy of the shooting script for an upcoming Ranma theatrical feature. This hoax was aided by the primitive state of native-Japanese anime coverage on the Web at the time, but was still unmasked rather quickly.
 * One script-format Ranma work needs to be mentioned: John Biles' Putting Your Heart In The Right Place. Nice WAFFic; established some fanon characterizations, most notably Nodoka's. Until 1996, Right Place was considered THE definitive Ranma fanfic.
 * Suburban Senshi, a comedy Mega Crossover based mainly on Sailor Moon and bringing in everything from Doctor Who to Sakura Taisen, is an odd case. The regular episodes are written in prose, but it also has a few episodes marketed as "The Movie", written as Script Fic, and plenty of segments of the characters on IRC.
 * This MST of an Evangelion script fic once, using the script format to give the first chapter's Cliff Hanger that little extra kick.
 * Thundermuffin's The Typical Gundam SEED Destiny, which is a parody that can be found on MAHQ's Mechatalk forums. It also includes a couple Gundam00 crossovers, and a parody of the (currently nonexistent) GSD film.
 * Evangelion R, written by Maher al-Samkari, is an example of this for Neon Genesis Evangelion. Unfortunately, while well-written in other ways such as character or plot the writer obviously did not know how to write a script.

Film

 * A fanfic author over at the MI6 (James Bond) message boards wrote a 116-page script on Timothy Dalton's proposed third Bond film, (adapting some other material too) accessible here.
 * A purportedly "leaked" script for The Third Transformers Movie is pretty much a script fic, and a highly illogical one to boot (time travel and G1 altmodes are heavily involved, oy...)
 * A surprisingly good Lord of the Lord of the Rings/Big Brother cross-over used this form. It was popular enough to run several seasons, was posted in episode form and held proper evictions based on reader feedback. Season 1 can be found here.
 * Larry Boy and the Little Man of Purpleness, a Star Wars/Veggie Tales crossover.
 * Aquaman: The Movie from TheGlen: "what if it was his job to clean up all the crap the other heroes dump in the ocean".

Literature

 * Tales of the Frog Princess has Ask The Characters, which is also a Fourth Wall Mail Slot. It can be read even by someone outside the fandom, and unlike most Script Fics, it CANNOT be performed as is. (Ghosts, imploding, magic, dragons, vampires transforming, Emma opening the pits of Hell, etc.

Live Action TV

 * Millennium Virtual Season Four was an entire season's worth of script fics written after the cancellation of the TV show, and was generally well-received—series star Lance Henriksen even noted that he enjoyed several of them.
 * Most MSTs are in script form, due to the way the "theater" segments work. Some writers, however, write the host segments in narrative form and the theater segments in script form.
 * Virtual Firefly, written as the "missing" second season of Firefly.
 * The very old but still rather good Blackadder: Serpent of the Seven Seas.
 * MZP is one of the largest websites dedicated to scripted fiction, containing many different virtual seasons—both original works and virtual continuations. The site includes continuations of Kolchak the Night Stalker, Millennium, Doctor Who, Star Trek and a spinoff from Alias.
 * the VPN hosts scripted fiction for a number of both original works and virtual continuations.
 * Gallifrey Base, the largest Doctor Who forum on the internet, has an extensive subsection devoted to this kind of format. Generally produced in virtual seasons by veteran posters, they most often feature past Doctors continuing on from after their "non-Fanon" deaths. Quality can vary wildly from the not too good to the surprisingly professional.
 * Virtual Mutant is the sister-site of MZP, and contains scripted virtual continuations of Buffy and Angel, as well as spin-offs Faith and Slayer Academy set in the same continuity. It also hosts several "non-MZP continuity" shows set in the Buffy Verse.
 * Just about every fan fic based on My So-Called Life falls under this category.
 * Star Trek: Voyager has The Voyager Virtual Season Project. Dozens of new stories set after the televised finale. If you want the plot in smaller, less-accurate doses they're partnered with Five Minute Voyager, so you can read the abridgements over on that site here.
 * Xena had the Virtual Subtext Seasons,essentially a continuation of the show with Xena and Gabrielle's relationship as canon. While the quality level wavers, they're not all bad and the format is surprisingly well done (with some exceptions). This troper was given to understand there was one where the show went on as-is, and one where Xena and Ares were in a relationship, but never managed to find them.
 * The Forever Knight virtual continuation FK4 is written in the format of a TV script with more specific details about camera angles and stage directions.
 * Power Rangers Take Flight, a hypothetical adaption of Choujin Sentai Jetman (and later, Choujuu Sentai Liveman), is written entirely in script format. Like an actual Power Rangers season, the storylines are even written with the use of Stock Footage from the Super Sentai season in mind.

Newspaper Comics

 * Calvin and Hobbes The Series takes this format somewhat, acting like it's an actual TV show (complete with Medium Awareness moments and a marathon with framing segments).

Professional Wrestling

 * On the other hand, Robert Lamb's Adventures of the nWo B-Team (Internet Archive link, broken formatting) uses the format very well, to keep all the dialog gags coming without a lot of narration getting in the way.

Tabletop Game

 * PRIMARCHS, a Warhammer 40,000 fic that's also a batshit insane Crossover Crack Fic; Better Than It Sounds if all the cries of AWESOME and WIN by its readers are to be believed.

Video Game

 * An odd example is Super Smash Stadium (based on Super Smash Bros.) which actually started out in prose but turned into a Script Fic soon after because of it focused on the fights as though it were a promotion complete with commentary. With its adaptation of Subspace Emissary, it has reverted back to prose.
 * And an odd variation in Kingdom Hearts 3, a hypothetical Kingdom Hearts game, written not as a script but rather as a video game walkthrough.
 * Hey, Ocarina! Being a "musical", it uses the script format to great effect where lyrics is concerned.
 * As well as a nonmusical Ocarina adaptation.
 * Brendan Namron: Ace Attorney is written in a style not unlike a transcript of an official Phoenix Wright game (such as this one). The author DOES attempt to open the first case with a prose format, however.
 * Phoenix's SSBB Case Files, being the series that inspired the above, naturally uses the same transcript method.
 * Fandemonium, due to video games being the closest thing you can get to describing it.

Western Animation

 * For some reason, most of the Road Rovers fics are Script Fics.
 * Maybe that's because there was only one season.
 * This is still somewhat popular among even the more skilled Futurama Fan Fiction authors, especially ones writing comedy, one-shot, or Original Flavor fics.
 * There's still some debate in Daria fanfic on the difference between script and prose fic... and when the debate first begin—the topic quickly became Serious Business.
 * The Vinyl Scratch Tapes are transcript fics, but close enough.
 * The Puzzle of Puzzle has "Establishing shot:" and "Scene change:" at the start of each scene.
 * This Kim Possible crossover has a script version and a prose version.

Real Life

 * Purple SUV, an ABBA fanfiction and parody of Yellow Submarine full of Crowning Moments Of Funny which is sadly not available anymore.