FScreenGrabber is a simple java application for grabbing a screen shot.
It allows a rectangle of the screen to be grabbed and optionally scaled, as shown on the screenshot below.
The program can be launched through java web start:
The source, a single .java source file, can be obtained below:
The source illustrates how to take screenshots with the java.awt.Robot, how to use XOR drawing and simple Drag and Drop support for images.