This blend contains three easy node groups to create metal-plastic-ceramic materials. The file includes 15 presets with example thumbs.
Basically increasing MirrorFac looks metallic and decreasing looks ceramic or plastic. Only changing diffuse color, coat color, IOR, roughness and mirrorfac you will get a huge number of materials. One node group called ContrastCoatedGlossy looks like metal paint.
The model has been made by Robin Marin (tuqueque). I have used the 2.61 bleder test version. You can download it here. It was created to test materials and it is a CC-BY lincensed blend.