Link: Several dozen Very Short Stories.
Some are quite good. Some went over my head. A few are US specific. Some are non-genre.
Authors include, among others, William Shatner, David Brin, Charles Stross, Vernor Vinge, Bruce Sterling, Stephen Baxter, Michael Moorcock, Neil Gaiman, Orson Scott Card, Howard Waldrop, Ben Bova, Ken MacLeod, Harry Harrison, Neal Stephenson, Ursula K Le Guin, Greg Bear, Gregory Benford, Cory Doctorow, & William Gibson.
- Arthur Clarke's famous micro-fiction, "siseneg", is also online - somewhere in this big DOC file that includes this "story" inline. Or at least was over 6 months back, when I found it.
- Via John Scalzi: For the last few days, original free fiction feed has been picking up micro-fiction from Thaumatrope - untitled "stories" no more than 140 characters (yes, characters, not words).