Archive of Our Own: Mostly for fanfiction but you can submit original work there as well. Fanfiction.net: Fanfiction website Fictionpress.com: Original work website, the sister site for Fanfiction.net Dreamwidth: More so a journal site but you can put literature there if you want. Doesn't seem to have that many users there though. Wattpad: Fanfiction and original work website, mostly for the uploading of books but you can still post one chaptered stories. Commaful: This is more so a interactive story book type of thing but, I think it still qualifies. It was literature on there.
That's about it, I'm sure there's plenty more out there than this.