For Y-Phil,

I mentioned integrating real-time lighting with HDR to change the mood of an environment. Below are two renders, one using the natural lighting from the HDR, the other given a warmer, overall tone.

                        

The difference between the two images is that I added a Blackbody node, set to 3600 degrees Kelvin, to the right image.  The Blackbody node was connected with a Mix node, as illustrated below: