You can use HTML color codes in most places where you type text:  chat, object naming, e-mail and such.

To use a different color, enter \# followed by the six-character hexadecimal code corresponding to the RGB (Red-Green-Blue) color you wish to use.  The first two characters are the red saturation, the next two the green and the last two are the blue.  The value of each color can range from 0 to 255 (00 to FF in hexadecimal).  The hexadecimal letters may be upper or lower case.  When a color code is used, text will continue to be that color until another code is used.  To turn off a color, reverting to the previous or default text color, enter \#. and make sure to include the trailing period.

Some common color codes include:

Red:  FF0000
Green:  00FF00
Blue:  0000FF
White:  FFFFFF
Black:  000000
Yellow:  FFFF00
Cyan:  00FFFF
Magenta:  FF00FF
Pink:  FF7F7F
Light yellow:  FFFF7F
Orange:  FF7F00

Contrast Codes
Contrast codes are like text color codes, except that they are relative to the User Interface color palette selected under the Options screen (press O to display by default, then click the Interface button and look for UI Palette).  The
syntax for their use is \#pcontrast[1-5][space].  A space must always follow the digit or the code won't work.  The command \#. will terminate the current contrast code as it does text color codes.