Let me ask the same, but with an added twist: what are your favourite specialty blogs? What do you think is a really great and insightful read, but maybe in some unusual area? Know of a great blog on knitting (or Lego, or kite-flying, or marathoning, or publishing, or whatever)? Please leave it in the comments.
One thing I really enjoy about blogs is that I get to read stuff from experts on pretty much any subject. I love reading about economics (e.g., John Quiggin, Brad DeLong and Greg Mankiw), marketing (e.g., Seth Godin, HorsePigCow), writing (Confident Writing), libraries (John Dupuis, Science Library Pad, Google Librarian blog), machine learning (Machine Learning), and lots and lots of other subjects. Pretty much every subject in the world can be fascinating, providing you’re talking to the right person!