Related Video: Confessions of an Erotica Writer

Kara's Porn for Women
No girl-on-girl pics here. One of the few sites targeted to heterosexual women, it has a small collection of stories, primarily involving consensual, one-on-one intercourse and oral sex. A collection of links points to stories with more slightly more diversity, but still with hetero women in mind. It also has articles, book reviews and pictures.

Free Best Sex Stories
This site has a large collection of stories with a range themes and an intuitive interface, so you can quickly click on what you're looking for, whether it's erotic poetry or anal sex stories. Readers are also invited to rate each story, making it easier to find something good.

Literotica
Stories on Literotica must be accepted for publication (ie, no self-uploading), and, in addition to 'How to' articles for authors, they have volunteer editors who will read and edit a story before it's submitted. This means the quality of material is (largely) better, and while the design isn't exactly cutting edge, it's easy to navigate. Themes vary widely, but the site does have limits, specifically no stories involving a character under age 18 and no bestiality, though "you can write stories about supernatural beasts like ghosts, unicorns, werewolves, etc."

Alt.Sex.Stories Text Repository
From “Damsels in Distress” to “Erotic Mind Control, anything goes at one of the oldest and largest collections of sex stories on the web. It's ad-free, so you won't get 45 browser windows full of porn popping up, but it's also unmoderated, which means anyone can post anything they want. For help separating the wheat from the chafe, click on "Collections," where you can browse stories culled by other erotica aficionados. WARNING: Because content is unmoderated and uncensored, some of it is extremely subversive. The faint of heart should browse elsewhere.