This is a very incomplete list of interesting people from the AI/ML community which I'll keep expanding in the future.

Jürgen Schmidhuber , Yoshua Bengio , Geoffrey E. Hinton , Yann LeCun , Andrew Ng

David Silver , Pieter Abbeel , Peter Stone , Matthew E. Tayler , Santinder Singh

David Aha , Nando de Freitas , Ray Kurzweil , Nick Bostrom , Eliezer S. Yudkowsky

Anna Helena Reali Costa , Felipe Leno da Silva , Rodrigo Cesar Bonini

Tensorflow (Google) , Theano , Keras , Neon , CNTK (Microsoft) , DSSTNE (Amazon) , Deeplearning4j

OpenAI Gym , Burlap , RLPy

http://waitbutwhy.com/
The content is very general and discusses technical and psychological topics with no fixed agenda; basically what the author thinks is interesting. For anyone interested in the development of future AI and technology, I highly recommend the article The AI Revolution: The Road to Superintelligence.

http://lesswrong.com/
Less Wrong is a community blog devoted to refining the art of human rationality for people who try to think rationally.

https://priceonomics.com/
Interesting articles about many topics, answering or discussing a variety of questions.

http://www.deepstuff.org/
Latest news in science research, breakthroughs and other Deep Stuff.

http://www.datatau.com/
News around data science, ML and AI.

http://www.popsci.com/
Popular science news collection.

http://singularityhub.com/
Singularity Hub chronicles technological progress by highlighting the breakthroughs, players, and issues shaping the future as well as supporting a global community of smart, passionate, action-oriented people who want to change the world.

https://www.hackster.io/
Hardware hacker community with a variety of projects using Arduino, Raspberry and their friends.

https://maker.pro/
Another maker site with tutorials and DIY projects using low cost hardware.

https://www.edge.org/
So, this is their own headline: To arrive at the edge of the world's knowledge, seek out the most complex and sophisticated minds, put them in a room together, and have them ask each other the questions they are asking themselves.

http://www.allaboutcircuits.com/
Electrical engineering online community that provides interesting articles, projects and useful resources for Electrical Engineers (and others).

https://www.speedwaymotors.com/info/school
Educational resources for teachers and students for automotive knowledge. Also has a section on electronic circuits for kids here. (Thanks for bringing this to my attention, Noah!)