http://reddit.com/r/[your_favorite_programming_language]

http://reddit.com/r/futurology

http://reddit.com/r/math

http://reddit.com/r/mathpics

http://reddit.com/r/statistics

http://reddit.com/r/probabilitytheory

http://reddit.com/r/electricalengineering

http://reddit.com/r/ece

http://reddit.com/r/netsec

http://reddit.com/r/physics

http://reddit.com/r/emdrive

http://reddit.com/r/artificial

http://reddit.com/r/machinelearning

http://reddit.com/r/neuralnetworks

http://reddit.com/r/MLQuestions

http://reddit.com/r/learnmachinelearning

http://reddit.com/r/mlpapers

http://reddit.com/r/computervision

There is really so much out there and everyone has there own personal interests. Just check out https://www.reddit.com/explore which will give you personalized recommendations based on the subreddits you are already subscribed to.