Some of the Best from Tor.com is a 10-book series with 10 released primary works first released in 2012 with contributions by Dale Bailey, Leigh Bardugo, Beth Bernobich, Jedediah Berry, Ben Burgis, John Chu, Tina Connolly, Paul Cornell, Cory Doctorow, Andy Duncan and 145 others.
Reactor (formerly tor.com) regularly publishes free novellas, novelettes, and short stories from various authors on their blog. Every year, a selection of these works are compiled and released in ebook format.