Update Added screenshots
I spend a lot of time working in front of a screen (many hours in a dimly lit room) and eye fatigue is an issue. A consistent color scheme, especially one which is easy on the eyes, is important — and it also helps to have way of doing that where the directives are not all scattered all over my Emacs-lisp setup. Enter Emacs Color Themes, available as the Debian package emacs-goodies. Aided with a HSL color picker, I set around trying to create a dark color theme for Emacs.
It does not help that I am blue-green color blind, so subtle variations are often lost on me. I do want to use color contrast to increase productivity, but I also want to avoid the jarring angry fruit salad look, and so I am in the process of crafting a logical color scheme that is high contrast enough for me, without being too unpleasing.
In circumstances where there a lot of related
faces that can be viewed, for example, the Gnus group buffer,
consistent and logical color choices are the only sane option. Gnus
groups can be news (bluish) or mail (greenish), have states (large
number of unread messages, normal, and empty). The large number
unread groups have highest luminosity (appear brighter), and the
empty one have lower luminosity (appear greyer), but have the same
hue and saturation. Sub states and group priorities are rendered
using a color series which has constant luminosity and saturation,
and vary in hue by a constant separation — so all the related
groups have the same brightness
({mail,news}/{unread,normal,empty}), and a graded selection of
foreground colors. It sounds more complicated that it looks. The
eye is drawn naturally to the unread groups, and first to the mail,
then USENET groups (which is my preference).
Similar color variations occur for individual
messages in a group; high scoring messages bubble to the top, and
have a higher luminosity. This color schema has made me slightly
faster at reading mail/USENET. In the message itself, quoted mail
messages from different people are color coordinated, with high
contrast between citations that are close to each other in the
hierarchy, so it is less likely that one misunderstands who said
what in a long conversation.
The resulting scheme covers programming languages, Gnus, Erc, mail, org-mode, CUA-mode, apt-utils, bbdb, compilation buffers, changelog mode, diff and ediff, eshell, and more. This has allowed me to consolidate all my color directives into a single file, and is in a format that might be usable by others. See the wiki page for details about how to use and switch color themes in Emacs.
Enjoy.