Science, tech, engineering & math
Simplifier on Neocities: a list of engineering DIY projects from the ground up. Probably useful in the event of an apocalypse.
Favorite page: the Electrolytic Rectifier.
Graphics, 3D, shaders, gamedev
Visual depth cues (by Piter Pasma): What properties of our visual system can you use in art to convey depth?
Personal note: Atmospheric perspective is by far the most useful one of the properties listed.
Collision detection (by Jeff Thompson): A comprehensive guide on implementing collision detection in 2D space. Has visual and code samples.