On-screen Ruler is a semi-transparent on-screen ruler to help you lay out GUIs and Web pages or measure anything on your screen. It supports units in centimeters, inches or pixels. In addition to using the mouse, you can keyboard shortcuts to move the ruler around the screen.
Download the ZIP package and extract to a folder of your choice. Launch Ruler.exe.

Writes settings to: Application folder.

Download: On Screen Ruler