Literotica

Literotica is one of the oldest web sites devoted to erotic literature, both with plot and without. Started in 1998, it is now home to close to a quarter of a million individual pieces of written fiction and has an Alexa rating of 1,638. It's the "America Online" of porn stories in that most people start there, some never leave, and lots of them are idiots.

Content is user-submitted and screened by the site's hard-working administrators, Laurel & Manu; only three things are hard rejects: underage participants, bestiality, and excessive gruesomeness. This has more to do with liability than censorship; as the largest and most visible erotic-literature website on the Internet, Literotica will be the first target on the list the next time a Jack Thompson starts an anti-smut crusade. So they'd rather be safe rather than sorry. (There are other websites out there if you want to read—or publish!—things Literotica won't touch, but some people have gone for years without figuring that out.)

This website provides examples of:

 * All Gays Are Promiscuous: Variously played straight and averted in the Gay Male section. (The Human Condition, the most popular story in the section, discusses the trope at some length, considering why it was true in the past, but rejecting that it should be or has to be true in the present.)
 * All Guys Want Cheerleaders: Played straight and averted, since some authors and readers prefer Nerds Are Sexy instead.
 * All Women Are Lustful: Combined with A Man Is Always Eager for optimum boinking.
 * Attractive Bent Gender: Inevitable in the Transsexuals and Crossdressers section.
 * Author Appeal: One assumes that the authors are writing about what interests them.
 * Become a Real Boy: A reasonably common plot in Nonhuman. Generally, becoming real requires love.
 * Bigger Is Better In Bed: Especially in Interracial.
 * Brain Bleach: You'll need it after reading the Erotic Horror section (and potentially the Nonconsent / Reluctance section, depending on content.)
 * Casual Kink: See BDSM, Fetish, etc.
 * Catholic School Girls Rule: Due to the age requirements, any story involving a Teacher-Student Romance will inevitably come close to this.
 * Conveniently Common Kink: The Fetish section.
 * Flame War: an ongoing one at the Loving Wives section. Some of its stories are vanilla "husband and wife doing etc" ditties, but other writers see the "adventurous married women" description and submit their cheating-wife stories there, largely for lack of any other category to put them in. This results in yelling matches in the comments sections, vote-bombs of stories a person doesn't like, and so on—with the poor bewildered author left to wonder why the entire Internet hates his story all of a sudden.
 * For that matter, even stories about cheating that are put in Erotic Couplings tend to get a negative reaction from readers who're the same gender as the person being cheated on (and a positive reaction from many individuals of the same gender as the cheater). Literotica has more male readers than female ones, so this can mean a 2-point difference in ratings between stories where men cheat on women and similar stories where women cheat on men. (So much for The Unfair Sex.)
 * Four Point Scale: both in letter, with scores varying between 1 and 5 stars; and in spirit, with scores weighted very highly towards the top end of the scale. On a site of 243,000 pieces of fiction (as of late December 2011), there are less than 500 stories scoring at 2.0 or lower. In comparison, there are close to 30,000 that have scored 4.5 and up.
 * Gender Bender: Whenever someone decides to write a fantasy story in the Transsexuals and Crossdressers section. All three laws apply, albeit with decreasing frequency as their associated number gets higher.
 * Good Adultery, Bad Adultery/Sympathetic Adulterer: As mentioned in Flame War above, if there's an adulterer in your story, prepare to get flamed if your cheater is the opposite sex of your audience. There are only two possible ways out: the cuckolded party gets revenge on the adulterer and lover, or the cuckolded party was an abusive twat to begin with. But even then, good luck.
 * Good People Have Good Sex
 * Grandma, What Massive Hotness You Have!: The Mature section.
 * Horny Devils: Erotic Horror.
 * Hot Librarian: The Nonconsent section seems to like this trope.
 * Hot Dad / Hot Mom
 * Ignored Epiphany: When the Mind Control section focuses a story on the controller rather than on the victim, there's often at least one moment where he realizes he's committed rape. Then he realizes that he's making his victim a better person, or that she enjoyed what he did to her, or (in at least one case) that the only way to escape punishment for his actions is to mind-control more and more people to add to his harem.
 * Incest Is Relative: The Incest section.
 * It's Not Rape If You Enjoyed It: Enforced. No stories can be tagged with any variant of the word "rape," and rape in which the victim doesn't enjoy it generally isn't allowed, but rape where the victim does enjoy it is allowed as "nonconsent."
 * Jumping the Gender Barrier: Transsexuals and Crossdressers, especially when magic is involved.
 * A Man Is Not a Virgin: Averted in some stories, especially in First Time, where the plot revolves around a young man losing his virginity to a more experienced partner. Played straight in most others.
 * Mind Manipulation: Mind Control, of course.
 * Mars Needs Women: Shows up in both Nonhuman and Sci-Fi and Fantasy. The only formulation more common than "Woman is raped by aliens For Science" is "Man is turned into a woman and raped by aliens For Science."
 * Mister Seahorse: See above.
 * Naughty Tentacles: Most likely to be played straight in Erotic Horror, though intelligent vines take this role with surprising frequency in all speculative fiction sections.
 * Noble Bigot: Used constantly in "Interracial" stories. Typically, one of the protagonists is a racist who has strong conceptions about the other race(s) in question. Depending on the story, those conceptions are either challenged or confirmed and be comes more justified as the protagonist is integrated into that culture. (For example, a white woman who is afraid of black men but starts a relationship with one and learns an Aesop either about how wrong she was, or how right she is.
 * Out With A Bang: Characters in the Erotic Horror section don't have a very high survival rate. (And then there are the ones who do survive . . .)
 * Playing To The Fetishes: Duh.
 * Porn Tropes: ...yeah.
 * Power Perversion Potential: Mind Control, and often Sci-Fi and Fantasy (though the latter can also use Deus Sex Machina.)
 * Professionals Do It On Desks: Many, many workplace-related stories.
 * Race Fetish: The entire point of the Interracial section.
 * Real Person Fic: The Celebrities section. ("Proper" fanfic is usually put here as well, since it doesn't have a section of its own.)
 * Roaring Rampage of Revenge: Pick a story with cheating in it. Is it rated 4.50 or higher? Chances are, this trope is how it ends.
 * Safe, Sane, and Consensual: Most of the time.
 * Schoolgirl Lesbians / Romantic Two-Girl Friendship
 * Serious Business: Many stories treat various forms of sex and sexual kinks as this. For example, BDSM is sometimes treated as a legal, binding contract or there's some sort of reprisal that is expected if the agreement is dishonored.
 * Spin-Off: "Chyoo", a Choose Your Own Adventure site with a Wiki-style interface, so that readers can not only choose their own happy endings, but write them too.
 * Vaporware: There's an announcement on its front page promising a software update within 3 months. This announcement dates back to 2006.
 * Stocking Filler: Not as common as you'd think, but still present.
 * Sturgeon's Law: A better aversion than most, but still in effect. There is a screening process, but it mostly involves searching for the few hard-reject buttons. Many specimens of dubious quality have still snuck through.
 * Suspiciously Vague Age: Common in "First Time," thanks to site rules.
 * Their First Time: The "First Time" category.
 * There Are No Girls On the Internet: Not as true as at other sites, at least partially because the women who are around tend to have correspondingly higher readership and popularity.
 * Totally Eighteen: Another option when dealing with the "First Time" quagmire. (A third is Nerds Are Virgins.)
 * Transsexual / Transvestite: Transsexuals and Crossdressers, of course. They tend to be wholesome more often than villainous.
 * Where Da White Women At?: Popular in Interracial.
 * You Sexy Beast: The Nonhuman section, and occasionally Sci-Fi and Fantasy as well. Popular subjects include vampires and werewolves, but subjects range from ghosts to robots (almost all of which have a Male To Female Universal Adaptor.)