One day while designing CSS based web site, it was matter of Pixels, and i needed to test wheather IE6 is calculated pixels correctly or not.
I googled it, and found 4 or 5 Rulers, but non of em was that professional or handy, just i had to use it since i have no alternative.
After days i built my own, it took 1 day of work. but i use this tool every day. I hope u like it.
Many styles, so u choose what u like, and what suits your design contrast and colors. Many Keyboard Shortcut keys for fast use. check about (F1) for Details. Width or height of the ruler is displayed, that makes it more quick, easy to use. Horizontal, and Vertical. Can resize, move, change direction .... all features with just quick buttons. Minimize To Tray, to be used when u need, without task bar space.