These are some of the blogs I like.  When this is not otherwise obvious, author names for individual blogs, or for group blogs with a primary author, appear in parentheses.  If you think I’m missing something I would enjoy, please let me know. All-time favorites are boldfaced.

• 80,000 Hours. The official blog of a nonprofit dedicated to figuring out how people can do the most good with their careers. 
• Andart II (Anders Sandberg). A blog by someone who holds the rare distinction of being one of the most impressive polymaths out there and one of the happiest people alive.
• Astral Codex Ten. Much more than you wanted to know about almost any topic.
• Bet on It (Bryan Caplan).
• Dan Luu.
• Fantastic Anachronism (Álvaro de Menard). Hard to categorize. See for yourself.
• Fin Moorhouse. Co-host of the excellent podcast Hear This Idea, inter alia.
• Giving gladly (Julia Wise). “Why well-planned giving is the most important thing you can do — and more fun than you thought.”
• Information Processing (Steve Hsu). Writings on cognitive genomics and other stuff. He co-hosts the podcast Manifold, also strongly recommended.
• Jeff Kaufman. Writings on a wide-range of topics.
• Jethro Kuan. Creator of my favorite Emacs package.
• Meteuphoric (Katja Grace). Musings about “human behavior, social institutions and rules, anthropic reasoning, personal experimentation and improvement, philanthropy, and the prospect of robots replacing humans.”
• Nintil (José Luis Ricón). “To estimate, compare, distinguish, discuss, and trace to its principal sources everything.”
• Overcoming bias (Robin Hanson). “No one is smarter than Robin Hanson.” — Bryan Caplan.
• Philosophical multicore (Michael Dickens). Insightful posts about some of the most important questions.
• Philosophy, et cetera (Richard Yetter Chappell). The best philosophy blog out there, bar none.
• Rational altruist (Paul Christiano). In-depth essays about the far future. Sadly, now defunct.
• Reflective disequilibrium (Carl Shulman). A wide-ranging blog by possibly my favorite living thinker.
• Scott Young. One of the few “productivity” gurus I respect.
• Shtetl-Optimized (Scott Aaronson).
• Stefan Schubert. A blog by an eminently sensible man.
• The GiveWell Blog. Research updates by the leading metacharity.
• The Polemical Medic (Greg Lewis). “Renaissance man affectations from a jejune junior doctor.”

See also: Effective altruism blogs