Pixel Ruler
Pixel ruler is a virtual ruler to count pixels. Staying over your Windows applications, it will help you to know the exact size and position of any photo, document, icon, HTML element, etc. You can rotate the ruler and change the skin.
http://www.mioplanet.com/products/pixelruler/pixelruler.exe - 717Kb - Download - Screenshot

Universal Desktop Ruler
Rulers are great for straight line distances, but would a ruler be a good choice to measure the length of a river or road? What if you are measuring a distance along roads from one city to another? How would you measure curved lines with a straight ruler? ... Additionally Universal Desktop Ruler has a screen magnifier function. ... Universal Desktop Ruler allows you to measure not only a straight line distance but any curved distance on the Screen. ... Universal Desktop Ruler allows you to measure quickly and accurately distances, areas and perimeters of figures on the screen.
http://avpsoft.com/download/udruler.exe - 901Kb - Download - Screenshot

JR Screen Ruler Pro
The JR Screen Ruler is a great tool that allows you to accurately measure anything on your screen. This is especially useful when measuring graphics, web page browser sizes or whatever. Screen Ruler can display Pixels, Inches, Picas, Centimeters. It also allows you to rotate and set transparent...
http://www.spadixbd.com/jruler/jrulerpro.zip - 352Kb - Download - Screenshot

Desktop Ruler
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, orientation,... As any ruler is more suitable for estimating than for actually measuring distances, Desktop Ruler incorporates a Precise Measuring Tool with adjustable zoom, capable of pixel level precision measuring of on-screen distances in any angle, not just along the ruler.
http://www.desktopruler.com/download/DesktopRulerSetup.exe - 1Mb - Download - Screenshot

MB-Ruler Pro
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 ruler is almost transparent so you can have it on the screen, while you are working with the applications below. ... The temporary objects can be saved as a stand alone application or as a bitmap. ... You can also draw points, lines, rectangles, ellipse, polylines, bitmaps and text as temporary...
http://www.markus-bader.de/MB-RulerPro/demodownload.php4?Language=E - 1Mb - Download - Screenshot

Cubic Ruler
Cubic Ruler is a very simple to use screen ruler.
http://www.soft.tahionic.com/download/Cubic-Ruler.exe - 146Kb - Download - Screenshot

MB-Ruler
A tool to measure distances and angles on the desktop. The distances can be measured in pixel, cm, inch, pointsor twips and the angle in radiant or degree. The ruler is almost transparent so you can have it on the screen, while you are working with the applications below. ... The temporary objects can be saved as a stand alone application or as a bitmap. ... You can also draw points, lines, rectangles, ellipse, polylines, bitmaps and text as temporary objects on the screen. ... Additionally it has a screen loupe and a RGB value window.
http://www.Markus-Bader.de/MB-Ruler/mbruler32.zip - 1Mb - Download - Screenshot

Flow Ruler for Outlook
Flow Ruler for Outlook The complete solution for your inbox. Flow Ruler allows you to automatically organize your inbox, eliminate spam, administrate contacts and appointments, and assign tasks through simple Rules which are graphically designed. Flow Ruler for Outlook is an Add In for MS... With Flow Ruler for Outlook you can also: ? ... With Flow Ruler for Outlook, you will be able to set rules for: ? ... Organize the Inbox, allowing the definition of different rules when a new email is received, for example, move the selected email to a specified folder, answer automatically, generate...
http://www.flowruler.com/downloads/FRSetup20.zip - 16Mb - Download

Perfect Screen Ruler
How to find out the size of something on the screen or to take a closer look at it? Use Perfect Screen Ruler. You will easily find out the size of any item on the screen, for instance, the size of a button or the distance between two points. You will be able to enlarge the image if necessary. ... It is useful when you measure some small images or when you need to study the enlarged area of the screen in detail.
http://www.styopkin.com/PerfectScreenRulerSetup.exe - 580Kb - Download - Screenshot

Reglo
Reglo is a versatile on-screen ruler that is perfect for designers, artists, webmasters, and anyone else who needs to handle graphics. In addition to supporting many different units of measurement, orientations, and ruler scales, Reglo has a wealth of handy features to make your job a lot easier. ... On top of all that, Reglo puts an icon in the taskbar status area that can be used to show or hide the ruler at any time. ... Reglo features a ruler guide, a magnifier, and one-keystroke positioning to the exact spot where the cursor is sitting.
http://www.basta.com/Software/SetupReglo.exe - 369Kb - Download - Screenshot