free ruler

Ruler Bars is a pop-up set of vertical and horizontal rulers on your screen.

It's a screen ruler for Windows.

A Ruler for Windows is a free on-screen pixel ruler for your PC.

Cubic Ruler is a very simple to use screen ruler.

Free Ruler is a free screen ruler for Mac OS X.

Perfect Screen Ruler allows you to accurately measure anything on your screen.

On screen ruler, configurable for horizontal, vertical, centimetres, inches

Use this tool to measure anything on your screen (mm, cm,px).

Can measure the distance (in pixels) between to points

DKRuler stays on top of all applications and file system windows.