make my own procedurally generated textures?

I’m not even sure where to start. I’m pretty sure that for the project I’m working on currently, the basic procedural textures that come with blender will not suffice. can new procedural textures be created with scripts, or is there another way? I could really use some advice and links to guides.

For blender internal, you need to add the texture to the source code and recompile. Cycles on the other hand allows you to create procedural textures either with nodes or using OSL. With nodes you can render your scene on GPUs, but some common operations like loops, matrices, etc., can be difficult to implement (even more difficult to manage dued to the quantity of nodes you need to perform those tasks).
In python you can create better/custom interfaces for your node_groups and even add more functionalities that can be performed before the render. Not sure if that works with OSL scripts though.