I learned this from bagginsbill, and it is very useful.

In a scene with NOTHING added, plug your procedure nodes into the Root node of the background. The background is not affected by the camera or the lights. Render to a square  dimension. I like 4096 pixils. Then export the render. I like to do it as TIF file, but any will probably do. You now have a texture that can be applied to an object  by attaching it to the the Diffuse channel of the Root Node, and you can see it in preview.

You may still want to produce your effect with a procedure, but you will be able to make a map of even very complex node set-ups to see how they look in preview, without having to render the whole scene.

With this method you can produce all kinds of maps. The material room is able to do things that are hard to figure out in Photoshop or Gimp.

Thanks BB!  :)

lmk

Probably edited for spelling, grammer, punctuation, or typos.