Classic Color Meter is a enhanced color meter replacement with added functionality:

Display modes

• RGB percentage
• RGB decimal
• RGB hexadecimal
• Hue/Saturation/Brightness (HSB)
• Hue/Saturation/Lightness (HSL)
• Y'PbPr and Y'CbCr
• CIE 1931, CIE 1976, CIE LAB, and Tristimulus values

Commands

• Lock cursor position / X axis / Y axis
• Adjust magnification (1x/2x/4x/8x)
• Adjust aperture size
• Show/hide cursor coordinates
• Update preview continuously
• Hold Color (allows editing of color in RGB and HSB modes)
• Save/Copy preview image
• Copy Color as Text, Image, or as a NSColor/UIColor/HTML/CSS code snippet
• Paste Text as color

Preferences

• Adjust aperture color
• Assign actions for clicking/dragging the color swatch
• Use lower-case letters for hex values
• Include pound sign prefix for hex values
• Show visual guides when locking cursor position
• Show component sliders when in Hold Color mode
• Assign global keyboard shortcuts
• Move mouse cursor with arrow keys