+11  A: 

I think you are looking for something like mwe-color-box.el

dsm
+1  A: 

If you need this to help editing, then I suggest turning on coloring the innermost sexp which contains the cursor with a different background color. At least I'm used to this and it is sufficient.

Levente Mészáros
Can you give an example of how to turn that feature on?
Alex B
+1  A: 

http://nschum.de/src/emacs/highlight-parentheses/ lets you highlight just the parentheses.

D-Coder