Does anyone know of any web resources or tutorials for HLSL? Google seems to be failing me on this one. All I can come up with is vague sample code with no real explanations.

Riemer's XNA Tutorials is an excellent reference for beginners. It walks you through the basics of using shaders and HLSL in Direct3D with not only code, but also in-depth explanations and diagrams that help illustrate how the rendering pipeline works. The actual application code it gives is in C#, but if you're working in C++ you should have no problem at all translating it.