I must confess that I sometimes find myself putting a ruler over the monitor to check distances. Mostly because I am feeling to lazy to take a screen shot and copy it in an image processing tool. If you're like me, then you might be interested in MB Ruler.
MB Ruler is a measuring tool box and can be used to measure and track elements on your computer screen. It features a triangular ruler that helps you detect angles, a coordinate finder with rotating coordinate bars, a distance measure tool and a system for marking points and coordinates. There is also a collection of customizable tools that vary from simple lines to the wonderful, flower of life. I highly doubt that MB put it there for its usefulness in measuring screen elements.
I like MB Ruler. Although I'll seldom use it, I think it's quite versatile in its design. I only wish it would not rely on right clicking so much.
MB-Ruler Pro TRIAL A tool to measure distances and angles on the desktop using different measure instruments like a trangular ruler, a coordiante system, a double cross hair, a polgon, a polyline, a circle, ... The distances can be measured in pixel, cm, inch, pointsor twips and the angle in radiant or degree. The... Download
Desktop Ruler TRIAL Desktop Ruler is, just as its name indicates, a virtual ruler utility/tool for your desktop. Need some freedom for your creativity? Small by size, our ruler grew into a very sophisticated product, where you can customize almost anything you can think of: size, colors, transparency,... Download