Screen Ruler Professional 188.8.131.52
Screen Ruler Pro was made for one single purpose -- to be the best screen ruler out there.
The tool is highly configurable and comes with different useful options (just some of them listed below):
* measure in pixels, millimeters, centimeters, points, inches
* define your own units
* horizontal and vertical guides
* customizable colors and translucency
* customizable tickers and direction