I added the following two items to my .emacs file, and they have changed my life:
(defun night-mode () (interactive) (color-theme-initialize) (color-theme-lawrence) (menu-bar-mode -1) (scroll-bar-mode -1)) (defun daylight-mode () (interactive) (color-theme-initialize) (color-theme-emacs-21) (menu-bar-mode 1) (scroll-bar-mode 1))
Both of these rely on the emacs "color themes" handler, but really, when working late at night when my eyes are tired, green on black seems to have a nice bit of contrast, whereas when working with a lot of light, the more traditional black-on-light-grey works well for me. By banishing the menu bars and scroll bar, I eliminate further sources of distracting contrast.
Which makes working with Emacs a heck of a lot more pleasant. I used to issue these commands by hand, but macro-izing them makes switching modes a much happier and more productive experience.