I have no idea where to find quality SFF short stories online. I want stuff by real authors and good stories. Stuff I want to read, but in little chunks. Well, I know Subterranean Online is publishing outstanding stuff. But, where else? Well, all of the Hugo Nominees are available online. I've read most of them by now (not all, but most)...and some are rather good. Some are just kind of blah, but I like them all for different reasons.
The Walls of the Universe -Paul Melko (my pick!)
A Billion Eves - Robert Reed
Inclination - William Shunn
Lord Weary's Empire - Michael Swainwick (have not read)
Julian: A Christmas Story - Robert Charles Wilson (have not read)
Yellow Card Man - Paolo Bacigalupi
Dawn, Sunset, and the Colors of the Earth - Michael F. Flynn
The Djinn's Wife - Ian McDonald (have not read)
All the Things You Are - Mike Resnick (my pick!)
Pol Pot's Beautiful Daughter - Geoff Ryman
How to Talk to Girls at Parties - Neil Gaiman (have not read)
Kin - Bruce McAllister
Impossible Dreams - Tim Pratt (my pick!)
Eight Episodes - Robert Reed
The House Beyond Your Sky - Benjamin Rosenbaum
One thing I find interesting is that so many of the stories are from Asimov's. So, A) The magazine is that amazingly good, or B) More of the Hugo voting public (WorldCon members) read Asimov's than any other publication. My guess is B.
I really appreciate, however, the Hugo nominees being available online. It's a good introduction to a lot of work and authors I may never have heard of or ever read.