Awesome thanks for the reply Ryan. Funny, I just thought about the idea of using the sphere following the camera on my lunch break 
It led me to wonder if the sphere could go into its own stencil buffer, but not be directly visible in the main render scene. Can that be done?
So say I want to use whatever texture is mapped to the sphere as a mask for some other effect in the main post process, can I pull that info from a stencil buffer and use it elsewhere?