TerminalColors is a SIMBL plugin that patches Apple's Terminal.app to add a color picker to allow the user to edit the ANSI colors.
Basically, a new inspector pane is added which enables you to select colors for all the individual ANSI colors. Why is this useful? The default blue and red colors used by the Terminal.app are nearly invisible to the human eye on a non-LCD screen. At that point, it seemed only right to provide functionality to cater to the potential whims regarding the other colors in the palette.