With the Material Nodes addon you can build materials from scratch or improve existing materials. At the moment it provides 19 node-groups which you can find in a dropdown-menu in the N-Panel of the shader editor. Remember that procedural textures are using less RAM memory and are fully animatable. My suggestion is to use procedural textures where you don't need really textures. In case there are node-groups missing, let me know and I will consider to add them in the next update.