Shader / Material Reference

I've decided I should make this a permanent and publicly searchable page on my blog (I keep losing links), so here's a place where I'll compile shader and material reference (code, scans, samples, best practice documents, reference images, etc) for myself and for other people working on such things. This will likely be primarily focussed on physically based rendering topics, but there may be other stuff here as well.

Pontificating on a Different Kind of Particle...

I have a tendency to write overly-long youtube comments. This one was on a video of someone showing off a high powered laser popping balloons...