Zowie.Fractals is a plugin for the popular Eclipse IDE that lets the user explore the set of complex numbers in the Mandelbrot set. When rendered visually, these can be quite distracting, and even pretty. It features intuitive mouse usage, the ability to load and save your work as PNG files, the ability to change the number of iterations, and full editor history integration.
XML Parsing in Java Kit is an Eclipse plug-in composed of three parts: cheat sheets, visual XPath, and XML templates. The cheat sheets describe Parsing XML in Java, with descriptions of using the DOM parser, validating documents, using XPath, character references, etc. An interactive example of using XPath expressions is included. Visual XPath is an XPath expressions visualizer. It lets you evaluate XPath expressions, and highlights the corresponding parts of the XML document of your choice in response. The XML templates can be useful for working with XML documents with a Java editor.