xcolorsel is a X-Utility based on this widget that allows you to display such
files ( /usr/lib/X11/rgb.txt by default ) together with tiles showing how the
color  looks on your screen.  Also a programmer may  (like with xfontsel) cut
the color names/definitions in various  formats (Colorformats and formats for
resourcefiles or C-sources) und paste them directly in his source codes.