Inigo Quilez
This is the website of a brilliant graphcs and demoscene programmer, and one of the creators of shadertoy. There are a lot of clever algorithms and tricks in here, especially for fullscreen-quad/shadertoy style demos.
Added by benjamin

Matt Phar's blog
The blog of Matt Phar, one of the authors behind the computer graphics textbook 'Physically Based Rendering, From Theory to Implementation', which goes into detail on the implementation of an educational renderer, pbrt. His blog contains some articles about solving specific graphics problems, as well as longer series. The series about the development of th e ispc compiler, and rendering the Moana Island dataset with pbrt are particularly interesting.
Added by benjamin