parenface.el, written by DavePearson, is an Emacs hack that lets you define a Face in which parens should appear – e.g., colored parentheses. It’s nice to “tone down” parens in Lisp source, for instance.
You can find it here:
http://www.davep.org/emacs/parenface.el
Dark blue parentheses:
(require 'parenface)
(set-face-foreground 'paren-face "blue4")