You can make a lot of things with cycles nodes that are GPU compatible:
When you want to learn to create procedural textures from scratch, start basic with texture coordinates and try to make some simple things using only the coordinates, square tiles/grids etc. Use existing textures or your own to distort and manipulate coordinates used for other textures. Making your own procedurals is really fun. GPU of course makes them more worth while. Just make sure to not have too many concurrent connections between nodes… MOAR SVM STACK SPACE NAOW!!!1!!111!!!11!!!1 …at least user adjustable for CPU:eyebrowlift:
Yeah, voronoi really needs more options made available. Also need material stats to be shown in node editor, like SVM elements used and total available, profiling, etc.