A software package a day: JRuler
JRuler is a single task utility that does one thing, but does it well. Often when doing development you wonder how much room you have to work with on the screen, but unlike the bad old days when you could just estimate dots (320 x 200 displays are something I remember and don’t miss) this can be difficult if the software you are working in (say, a browser) doesn't provide rulers.
JRuler works on any 32 bit version of Windows and provides a simple way to measure anything that appears on your monitor. The user interface is as simple as the task: move the ruler to what you want to measure and hover over the end point to see the distance in pixels, picas, inches or centimeters (all the latter based on the pixels per inch reported for your monitor). Flip the ruler vertically if you need… and that is about it.
Small utilities like this are some of my favorite: the need is obvious yet none of the system tools provide a good solution. This one is free and the only shortcoming is that it can only do horizontal or vertical measurements (which is all I need for programming). A pay utility that is more flexible is Screen Calipers. It has far more features beyond those of JRuler… but for me I like the simplicity of JRuler.