The following guide will guide you in the process of creating a sample theme, the debianfun theme which is both simple and good looking:
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#
# gnu/debian.. gnu/popular gnu/linux gnu/dist
#
needmod number-extra
needmod themecompat
needmod color
PS1="$u`color fgred`@`color`$h "$w"`color fgred`$b `color`"
TITLE="terminal::$TEXTNUMBER"
XFONT=lime.pcf.gz
SIZE_X=110
SIZE_Y=25
## Debian swirl which is shown one second upon startup
IMAGELOGO=debian.xpm
## Debian swirl, dull version in the background.
IMAGEFILE=debian2.xpm
## Color definitions
ANSICOLOR_BRIGHTRED=cc1111
ANSICOLOR_BRIGHTBLUE=553333
ANSICOLOR_BRIGHTGREEN=442222
ANSICOLOR_BRIGHTCYAN=662222
ANSICOLOR_BRIGHTYELLOW=883333
ANSICOLOR_BRIGHTMAGENTA=554444
ANSICOLOR_BRIGHTBLACK=330000
ANSICOLOR_BRIGHTWHITE=665555
ANSICOLOR_YELLOW=883333
ANSICOLOR_RED=880000
ANSICOLOR_GREEN=885555
ANSICOLOR_BLUE=553333
ANSICOLOR_GREEN=442222
ANSICOLOR_CYAN=662222
ANSICOLOR_YELLOW=883333
ANSICOLOR_MAGENTA=554444
ANSICOLOR_BLACK=330000
ANSICOLOR_WHITE=665555
CURSORCOLOR=$ANSICOLOR_RED
FGPOINTERCOLOR=$ANSICOLOR_RED
BGCOLOR=dedede
FGCOLOR=000000
## transparency off
BGBRIGHTNESSRED=256
BGBRIGHTNESSGREEN=256
BGBRIGHTNESSBLUE=256
BGTRANSPARENCY=0
## Information about the author
THEME_AUTHOR=''Arne <arne AT users.sourceforge.net>
THEME_URL=http://www.debian.org/
THEME_COMMENT=''Noticing a slight bias toward a certain Linux distribution? must be a coincidence...''