With screen sizes, even on laptops, rapidly expanding and external monitors now well above 20 inches, sometimes it can be useful to be able to measure distances on your screen.
StormRuler is a simple utility that enables you to measure objects and distances across your screen. All that's required is that you place StormRuler next to the object you want to measure and anchor StormRuler at the point you want to start measuring from.
If it doesn't have much real practical use for most users, StormRuler does at least look quite cool with semi-transparent skin. However, unfortunately it doesn't seem to work in Vista yet and is only available for Windows 9X/2K and XP. It's rather annoying as well that you can only measure in pixels - there's no way to change the unit of measurement to imperial or metric units.
StormRuler is useful for designers or anyone else that needs to measure the pixels of a certain image or file and has no other way of doing so.