The following is an xterm color chart, providing visuals for colors available to use in xterm. Updated removing duplicates and fixed issues with two word colors. These colors are from the command "showrgb" and can be used for various X11 things.

The primary spot I use the colors for is setting the xterm foreground color and xterm background color. I'll use different color backgrounds in xterm to tell me what type of server I'm on, just a visual cue. So a red background for a production server, blue for QA, etc...

Example: xterm -fg LightGoldenrod1 -bg CornflowerBlue -e 'ssh server.com'

If you want to use these colors to customize the xterm background or other terminal settings by default, You can create the file .Xdefaults in your home directory and configure using the following, more info available here on .Xdefaults

xterm*Background:               CornflowerBlue
xterm*Foreground:               LightGoldenrod1
xterm*cursorColor:              red
xterm*pointerShape:             arrow
xterm*pointerColor:             blue

Customizing Xterm Font

You can also customize your fonts in xterm, which sometimes is tricky, there are lots of different flags to set font name. Here's how I customize my xterm including setting font, font size, terminal size, scrollbars and scrollback on Mac OS X.

xterm -fa Inconsolata -fs 12 -geometry 100x40 -sb -sl 5000 -e ssh -X server.com &

XTerm Colors - Color Chart Names

If you need the RGB values, you can View Source or use the HTML inspector in your browser, each color is inline CSS.