There will be a free preview of HBO & Cinemax on Frontier FIOS November 17-20.
Free Preview Begins: November 17, 2017 (Friday)
Free Preview Ends: November 20, 2017 (Monday)
DirecTV is having an all premium channel free preview over Thanksgiving weekend. This includes free HBO, Cinemax, Starz, and Showtime!
Free Preview Begins: November 23, 2017 (Thursday)
Free Preview Ends: November 26, 2017 (Sunday)
There will be a free preview of HBO and Cinemax on Verizon FIOS November 14-20.
Free Preview Begins: November 14, 2017 (Tuesday)
Free Preview Ends: November 20, 2017 (Monday)
Dish Network will be showing a free preview of HBO and Cinemax November 17-20.
Free Preview Begins: November 17, 2017 (Friday)
Free Preview Ends: November 20, 2017 (Monday)
There will be a free preview of SundanceTV on Dish Network November 16 ā December 5.
Free Preview Begins: November 16, 2017 (Thursday)
Free Preview Ends: December 5, 2017 (Tuesday)
Source: freepreview.tv & my email.
This is all I know of right now, will add others as I learn more. Feel free to add any you come across.