Look at this recent portrait:
You will see standard lighting with a softbox on camera right, a fill light on camera left, a hair light behind him, using a Honl Snoot, and a background light aimed at the background.
This background light has a subtle blue Honl Photo gel on it. Can you see how much of a difference that makes? No gel would mean a grey background, and blue adds a touch of interest as well as a hint of corporate soldity.