The color values of a region of an image may be acquired from within the Viewer window (see here for details). The Pixel Analyser does the same thing, but offers far more functionality.
The pixel analyser will present the color values of any pixel that lays underneath a Command click in the Viewer window. This value is visualised in the 'current' preview box, located on the left hand side of the analyser. The RGB and HSL values are presented as numerical values. More usefully, it will also present the minimum, maximum, average and median values. For single pixel values, this is irrelevant. However, a region of colors can be selected by Command Shift clicking in the viewer window. Also... a Command Drag will return a trail of points, which is useful for non-rectangular selections.