To my knowledge, there are three online OpenGL tutorials which stand head and shoulders above the rest:

I recently started porting the first of these from C to Python.

https://bitbucket.org/tartley/gltutpy

This is primarily for my own benefit, and I’ve only done the first two chapters thus far, but others may find some use in seeing the translation. If anyone else is interested enough to want to contribute, drop me a line and I’ll happily grant commit rights.