This is a detail shot of a gourd shader that I wrote in RenderMan. It's been a while, but if I remember correctly, this was one that was designed from inception to be purely code based. Completely procedural. In other words, I didn't paint any of this in Photoshop. This was generated completely by text that I coded for RenderMan, and rendered with the Blue Moon renderer.
That makes it the texture equivalent of a vector graphic; I could zoom in on this in Maya, and render it out and get very high quality at any zoom level. It's a fascinating way to work, and while it's not always practical, it's good to know the option is there. It's processor intensive, so it's really only viable in preproduction (or frame by frame rendering like Pixar's work) as opposed to a real-time engine like a game console.