An Emacs color-theme version of Ethan Schoonover's "Solarized" theme pair.
M-x color-theme-sanityinc-solarized-light M-x color-theme-sanityinc-solarized-dark
See http://ethanschoonover.com/solarized for more info.
Thanks to Greg Pfeil for color-theme-solarized, of which these themes are a different formulation, providing a different set of faces and a few different choices. You might want to use his version instead.
Note that, depending on your version of Emacs, the colors in this theme may not be rendered accurately. See, for example, this OS X Emacs bug.