Now updated for RenderMan 21 and Maya 2017.
When you want variation from your RenderMan shader, you could use Primvar. This RenderMan functionality gives you the ability to use only one shader for many objects and create variety at render time. But the process of assigning these attributes could be time consuming and discouraging for an artist.
To make this process easier, I created a tool that speeds up the process. Primvar Manager for Maya.