Aljoscha Rittner created a very cool plugin sometime ago. You'd use it when creating documentation (helpsets, HTML files, PDF docs, etc) for your NetBeans Platform application, while putting the screenshots together.
Read more about it here (in German, in Alojoscha's blog) and here in English, by Toni Epple.
Here's some screenshots of my own, showing the plugin in action:.

As you can see, after taking a screenshot, the plugin is able to introspect the screenshot itself and give you the opportunity to crop where necessary. Below, for example, is how I make a screenshot of the Options window:

,,,and not only in NetBeans IDE can this plugin be used, of course, as can be seen here in the Paint Application, which is bundled with NetBeans IDE (and below you also see the magnifier in action):

Get it here in Aljoscha's blog. It's really cool and I'm going to be using it a lot!