I work mostly with jewelry renders. The HDR editor is a fantastic tool. But with small shinny objects and multiple pins, it's often hard to tell which light pin is affecting an area of the model.
A trick I use is to set the pin color to red temporary, then I can see exactly how that light lands on the model.
A feature I'd like to see is a hot key (R) that changes the active pin color to red when pressed. This would make identifying and moving a light pin a lot easier without going back and forth to the color selector window. On second thought, maybe also add a hot key G=green. You know, for the guys who render Ferraris.
Ed
I think a very early cut of HDR light studio (maybe v1) had an HDR that was basically a matrix of coloured 'lights' to help you figure out where you were. It was very handy.