Anderbo for Online Short Stories, Poetry, Facts, and Photography.
I don't keep up with many online sites, but I do really enjoy McSweenys. However, Anderbo is a site that has a bunch of fiction. Short stories, poetry, "fact" stories, and photos. The stories are all around 3,500 words, so they're all pretty quick to read. The poetry is pretty, and I like a good amount of it. You can submit to them. Short stories have to be up to 3,500 words. Poetry requires up to 6 poems. Fact stories need up to 1,500 words. I found this site more recently, in the past few months, and haven't fully read through all of it, but what I have read has been cool. Not much collaboratives, but the authors are all interesting.