antirez - Salvatore Sanfilippo - author of Redis and all around C expert
Concurrency Freaks - A web site dedicated to Concurrent algorithms and patterns.
Julia Evans - has a knack for explaining things clearly
Brandur - his technical posts are informative and beautiful to the same degree!
Sacha Chua - awesome Emacs and life tips
David Nolen - prominent Clojure developer.
Dan Luu - is full with well researched articles on a myriad of topics.
The ryg blog | When I grow up I'll be an inventor - Blog of Fabian Giesen which is full of articles on high performance computing.
Blog | Paul Cavallaro - Another blogger with very good high performance computing articles and writeups about research papers in same areas.
Stephen Diehl - One of the best blogs when it comes to Haskell.
John A De Goes - A treasure trove advanced Scala articles.