Apache Cocoon is a Web development framework built around the concepts of separation of concerns and component-based Web development. Cocoon implements these concepts around the notion of "component pipelines", each component on the pipeline specializing on a particular operation. This makes it possible to use a Lego(tm)-like approach in building Web solutions, hooking together components into pipelines without any required programming.
Apache XML Graphics Commons is a library that consists of several reusable components used by Apache Batik and Apache FOP. Many of these components can easily be used separately outside the domains of SVG and XSL-FO. You will find components such as a PDF library, an RTF library, Graphics2D implementations that let you generate PDF and PostScript files, and much more.
While the author of BSAX-J has not yet come to a final conclusion about the need for a binary XML format, BSAX is his idea of one possible encoding that leverages other XML prior art (SAX events and UTF-8, in particular). It is complete in that it can be used to perform round-trip conversions from textual XML to SAX events to BSAX binary streams, and back to SAX events and textual XML. The test code in the distribution does exactly that for a simple example XML file, and measures the difference in file size (the file is slightly smaller for the BSAX encoding of the sample file) and the difference in read time (the read time is significantly faster for the sample file).
Bambookit GUI is a completely XML-scriptable user interface to build real-time interactive Web application front-ends. Applications occupy 100 Kb of device memory and run on any Java-enabled browser. Users can move windows, resize containers, scroll and sort tables, lists, trees, see real-time data display, use a layout manager, and more. All rendering and event handling is managed in the XML scripts.