This is a good month for free online fiction!
A Dance Across Embers, by Lisa Mantchev
Excerpt from a Letter by a Social-realist Aswang, by Kristin Mandigma
Lone Star Stories
Stickmen, by Forrest Aguirre
Odd Jack, King of Monsters, by Claude Lalumiere
Black Betty, by Ben Peek
Longtime Gone, by Kurt Dinan
Hatchie Bottom, by Barry Hollander
Shooting Dogs for Fun and Profit, by Alex Wilson
Strange Horizons (new fiction weekly)
Catherine and the Satyr, by Theodora Goss
The Master, by Lavie Tidhar
Fire in the Lake, by Chris Roberson
Show of Hands, by David Prill
I only listed the Subterranean stories which I know were published in October. There are three others from Kealan Patrick Burke, Jay Lake, and Livia Llewellyn published in September.
These are all markets I read on a regular basis. I'm sure there is plenty of good free online fiction out this month which I am not reading and so have not listed here.