This is a list of some of the blogs I read. (Like all such lists, it’s incomplete and outdated.) I occasionally even write short introductions, which can be found under the blogroll category on the all categories page
in no particular order
Scott Aaronson blogs at Shtetl-Optimized. Quantum computing and complexity theory and tangential subjects.
Bill Gasarch and Lanse Fortnow blog at Computational Complexity about guess what. Earlier post. (… why I read so many complexity theory blogs if I’m not even specializing in complexity theory? One needs hobbies?).
Andrew Gelman has a very active blog: Statistical Modeling, Causal Inference, and Social Science. Also occasional contributions by Bob Carpenter, Aki Vehtari, and others.
Simo K. Kivelä blogs about (numerical) maths in Finnish.
Mike Glyer updates about science fiction news at File770. Very prolific.
Jukka Kemppinen. Half of the time I don’t have any idea what he writes about, but more often than not, it’s interesting. Maybe one broad thematic descriptor would be ‘‘cultural history of Finland’’? (In Finnish.)
David Richeson / Division by Zero. Mostly geometry.
SlateStarCodex. The weird one.
C.S. Kaplan. Geometry. General math and CS.
While My MCMC Gently Smaples. “Bayesian modeling, Computational Psychiatry, and Python”, by Thomas Wiecki.
Isaac Slavitt. No posts recently, but archive has nice stuff about computational methods / statistics with Python / Julia.
Bruce Schneier. Cybersecurity. Cryptography.