Tips, tricks, insights. Go here on a regular basis to learn and keep up.
Not as many posts recently, but very thoughtful and smart posts over the past couple of years. Worth reading through.
Filament Group Lab
Called ‘lab’ but mainly a blog or at least place with lots of great articles. These guys are great.
A List Apart
Venerable and still going strong.
Responsive web design posts, how-to pieces, thoughts
Blog about the engine behind Safari, Chrome, etc.