Mike Flannagan (who has adapted a few Stephen King books) has the rights to King's entire The Dark Tower Series. He's written the first scripts, and King is apparently pleased with them. The movie adaptation was awful.
Flannagan is also doing a Carrie series set in modern times, on Amazon, I believe. King was not on board at first, but after seeing some scripts, he is now enthusiastic about the new series. Flanagan was previously on Netflix and did some excellent series there.