A number of the tor.com novellas are on sale for 99¢ at some of the US etailers right now.
Here's a price-sorted search on tor.com from
Amazon US. I confirmed that some of these were 99¢ at Kobo also.
The titles on sale include:
The Last Witness by K. J. Parker
Of Sorrow and Such by Angela Slatter
Sunset Mantle by Alter S. Reiss
The Shootout Solution: Genrenauts Episode 1 by Michael R. Underwood
Domnall and the Borrowed Child by Sylvia Spruck Wrigley
The Emperor's Railroad (The Dreaming Cities) by Guy Haley
The Drowning Eyes by Emily Foster
Patchwerk by David Tallerman
Pieces of Hate (The Assassins Series) by Tim Lebbon
The only one of these I've read (and enjoyed) is Of Sorrow and Such. Off the top of my head, I've read at least four others from the imprint, and I'll definitely scoop up several more now.
I'm not aware of any of these titles being prior Tor giveaways, but they have given away others directly from tor.com, and the novellas are also sold in bundles, so you may want to check your library rather than rely on your etailer to warn of a prior purchase.