These are a few of the WebGL resources around the web that I've found helpful
- The Official WebGL spec
- WebGL Extension registry
- The LearningWebGL.com lessons
- MDN's WebGL page
- Three.JS
- Aerotwist.com
- Gregg Tavares' WebGL posts
- Codeflow.org
- Learning Three.js
- ShaderToy
- Chrome WebGL Experiments
- Khronos WebGL page