Daily Science Fiction publishes one science fiction story every single day. They pay for all of their stories. They pay 8 cents a word, up to 1,500 words.
They are particularly interested in publishing “flash series — three or more flash tales built around a common theme.”
They have thorough guidelines. And even though they have a section called “not so helpful hints,” it is actually helpful. I particularly appreciate their “PS:”
“PS We’d like to emphasize that guidelines aren’t worth the paper they’re printed on (which in this case is no paper at all). Splurge for a free email subscription, or if you can’t afford free, browse the archives here on the website. Read, and get a feel for what Daily Science Fiction publishes. We always want new and different work, of course, but you can get a real tactile sense of this or any other publication only by reading it.”
They are absolutely right: The best way to know what any publisher wants to publish is to read what they’ve previously published. More than once, I’ve found contradictions between what is published and what a publisher says they publish in the submission guidelines.
To learn more, be sure to read their submission guidelines.