One of the things we learned about in our Blender Bender group is using dirty vertex colors to create shading on our 3D models. What a wonderful and powerful tool!
You can apply dirty vertex by going into vertex paint mode and apply dirty vertex via “Paint.” Or, to have more control you can use nodes by adding an Attribute node.
See my node setup below:
Want to learn more? Come into Second Life and look up the group Blender Benders.
I also found this short tutorial on the web: http://adaptivesamples.com/2013/08/07/commonly-ignored-feature-6-dirty-vertex-colours/