Really Good OpenGL Tutorial

I definitely recommend this tutorial: http://duriansoftware.com/joe/An-intro-to-modern-OpenGL.-Table-of-Contents.html

Its the clearest explanation of opengl I've seen, and it gets into some interesting things in the later chapters. It looks like there was more planned that never got written, but what is there is very helpful.

As a side note, when he talks about matrices and using them for effects, he is implicitly using one of the concepts found in this article: http://conal.net/blog/posts/reimagining-matrices

Conal Elliot always has interesting things to say, and in this case he mentions that multiplying matrices is the same as composing them. This means that to compose linear transformations in OpenGL code, you simple multiple the matrices that define those transformations. Good stuff.