What is the Emacs mode or package that highlights Lisp forms changing the color of the backgrounds so that the form you are in has one color, the outer form another, the outer o
I don't use it, but this might be what you're looking for: http://www.emacswiki.org/emacs/RainbowDelimiters
You may want to try mwe-color-box (screenshot below) or read Five approaches to s-expression highlighting by Lemondor.
(source: foldr.org)
Take a look at screenshots here http://lemonodor.com/archives/001207.html, may be that is what you want.