When the css-tricks site goes down, we all realise how much we rely on it. Chris and his team write the best, most thorough and reliable, stuff. I go back to the almanac on selectors *constantly.* Also loving the beginners series to recommend to newbies.
Server run by the main developers of the project 
It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!