GLSL Reference Pages
A list of all the built-in functions in GLSL ES. It's a pretty small language!
WebGL Cheat Sheet
Quick reference for WebGL and GLSL ES.
Code to generate noise in GLSL ES.
A WebGL live editor for pixel shaders. You can also save and share. By mrdoob et al.
Shaders by Iñigo Quilez et al.
Make a shader that responds to music.
Iñigo Quilez's tutorials
Advanced techniques in pixel shading from demoscene master Iñigo Quilez. This book in its final form will aim to give enough foundation for you to tackle anything on Iñigo's site.
Iñigo Quilez's live coding videos
Watch how a sorcerer goes about casting his spells.
Into the Continuum
Animated graphical mathematical explorations using Mathematica. Not GLSL, but similar in spirit.