Blogs I like:

Concrete Nonsense
Theoretical Atlas
Neverendingbooks
Motivic stuff
Rigorous trivialities
Secret blogging seminar
Terence Tao's blog
Gowers's Weblog
The n-Category Cafe
Not Even Wrong
This Week's Finds
Greg Mankiw's Blog
Marginal Revolution
Cafe Hayek
Econlog
Overcoming Bias
Delta Epsilons
Musings
Edge
Shtetl-Optimized
Logic Matters
Crooked Timber
The Volokh Conspiracy
Real Clear Politics
God Plays Dice
David D. Friedman's Blog
Embuches Tissues
Gravity and Levity

Apparently dormant blogs:
Mathematics and physics
The Rising Sea