I've been trying out a lot of the brush tools to get used to them. I've been creating textures entirely inside zbrush without using any actual texture images. After an hour of work, the image below almost looks it's a photo of bizare organic blocks. I essentially carved the image out of a blank canvas and then air brushed color over it. In fact, the original file still contains depth information, so I can sitll pull things forward and recess them back into the canvas.