Template:o can be used to quickly colour a span of text olive (eg: for block quotes, or for examplars) if the first parameter is left as a null -
or to colour a span of text with any given colour, such as an RGB hex code, #C9E72A, or any of the web named colours such as red, blue, green, mocassin, or darkorchid, etc, etc.

See Wikipedia:Web colors for a list of colours.