Smashing Magazine (@smashingmag)
First suggested to me by Rich (@rmanalan), Smashing has tons of resources for web designers/developers, ranging from operational stuff like how to work with clients to free-to-use fonts and icon packs to how-to tutorials.
Here are a couple sample posts I liked recently:
I especially appreciate that they publish entire posts (vs. excerpts) to their feed, especially since they do a lot of long posts with graphics, and the Related Posts are very useful if you find something that interests you.
Here are a few I liked recently:
JQuery for Complete Beginners: Part 1 (there have been four parts so far)