Black
DarkRed
Red
Magenta
Pink
Sienna
DarkOrange
SandyBrown
Orange
Wheat
DarkOliveGreen
Olive
YellowGreen
Yellow
LemonChiffon
DarkGreen
Green
SeaGreen
Lime
PaleGreen
DarkSlateBlue
Teal
MediumTurquoise
Cyan
PaleTurquoise
Navy
Blue
RoyalBlue
DeepSkyBlue
LightBlue
Indigo
SlateGray
Purple
DarkOrchid
Plum
DarkSlateGray
DimGray
Gray
Silver
White
If you want more colors, then you can use the HEX color code generator to get more of them.
Also, [COLOR=#eeeeee][/COLOR] is invisible (not really invisible, it just matches perfectly the background color of Toribash forums).