Features:
• A horizontal and vertical ruler which can be used independently or simultaneously.
• Measurement in Pixels, inches, picas, or centimeters.
• Automatic alignment of rulers.
• The ability to group rulers and move them around as a unit.
• Shadowless rulers with customizable transparency.
• Interactive tick marks which follow the mouse location for more precise measurement.
• Independent resizing of rulers, from 200 pixels to 5000 pixels in length.
• Single key shortcuts for most ruler functions.
• Conversion assistant to set ruler resolution based on screen size and resolution.
• Unit Converter utility for converting numbers Between different Units Of Measure.
• Did I mention it's free?