A small procedual texture experiment which never got past these three test renders. While this is 2D, it too has been realized in Blender: An "Emission" material which procedurally generates the texture acts as a pixel shader.

2D image, abstract shapes. At the outside, a dark blue quare grid at 45° angle with light blue shaded square tiles. Going in, the squares increasingly get wobbly and distorted, transitioning towards a yellow circle in the center, with the occasional shades of green in between. Similar picture as the first one, but the grid tiles are a bit larged and the colors more muted. To the bottom right of the yellow center, there are two small red circles filled with a square grid of their own. Same image as the second, but with a different seed.