I learned the basics of OpenGL from NeHe many years ago, and while things have gotten better, I can't recommend the site anymore. It's all written for old-school OpenGL (3 and below) and is generally a compendium of what you shouldn't do when writing OGL code. I still love it, but it's a bad resource for people new to OGL.
The Orange Book, Red Book, Lighthouse3d tutorials, and general experimentation. One nice thing about WebGL is that the cruft is largely gone, due to its ES parentage. This means that a lot of old tutorials are completely irrelevant, but that you can safely use just about everything without running into horrible practices. (Not that there aren't plenty of pitfalls left.)
