This is a very incomplete list of interesting people from the AI/ML community which I'll keep expanding in the future.
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.
Less Wrong is a community blog devoted to refining the art of human rationality for people who try to think rationally.
Interesting articles about many topics, answering or discussing a variety of questions.
Latest news in science research, breakthroughs and other Deep Stuff.
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.
Hardware hacker community with a variety of projects using Arduino, Raspberry and their friends.
Another maker site with tutorials and DIY projects using low cost hardware.
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.
Electrical engineering online community that provides interesting articles, projects and useful resources for Electrical Engineers (and others).
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!)