Emacs can be customized in several ways in addition to the standard customization buffers and the Options menu.
The standard Mac / GNUstep font and color panels are accessible via Lisp commands. The Font Panel may be accessed with M-x ns-popup-font-panel. It will set the default font in the frame most recently used or clicked on.
You can bring up a color panel with M-x ns-popup-color-panel and drag the color you want over the Emacs face you want to change. Normal dragging will alter the foreground color. Shift dragging will alter the background color. To discard the settings, create a new frame and close the altered one.
Useful in this context is the listing of all faces obtained by M-x list-faces-display.
The following customization options are specific to the Nextstep port.