Free Ruler is a screen ruler for OS X with many intuitive features. Great for Web developers, graphic designers and programmers.

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.

• Universal Binary!
• Recompiled using latest version of REALbasic (RB 2007r1)
• Had to remove transparency support for now - RB2007 doesn't support WindowAlpha plugin..