[mcn]

Someone (sorry for not noting your name) suggested dimming/graying the parentheses in lisp modes and gave this elisp snippet to do it. I find that I prefer reading lisp with dimmed parentheses.

(defface paren-face '((((class color) (background dark)) (:foreground "grey20")) (((class color) (background light)) (:foreground "grey70"))) "Face used to dim parentheses.")

(add-hook 'scheme-mode-hook (lambda () (font-lock-add-keywords nil '(("(\\|)" . 'paren-face)))))

I also came across a blog post[1] which includes a slightly more complete solution.

http://briancarper.net/blog/492/

[evangineer]

There's also Dave Pearson's parenface.el:

http://www.davep.org/emacs/parenface.el