Flying Saucer is an XHTML renderer written in Java. It's 100% Java, not a native wrapper, and it only handles well-formed XHTML + CSS. It is intended for embedding web-based user interfaces into Java applications (ex. web photo album generator, help viewer, iTunes Music Store clone). It cannot be used as a general purpose web browser since it does not support the malformed legacy HTML found on the web, though recent work on compatibility libraries may be enough to do what you need. You may be able to work with legacy HTML (e.g. HTML that is not well-formed XML) by using a pre-processor that cleans it up; there are several of these, including JTidy and TagSoup.
xfpt is a program that reads a file of plain text that contains relatively simple markup, and outputs an XML file. It is intended to simplify the management of XML data. It is not a program that attempts to turn a plain text document into XML. Markup within text is introduced by ampersand characters, but is otherwise "soft". You can define what follows the ampersand, for example, &" to generate a "quote" element. There is also a macro facility that allows for higher level concepts such as chapters, displays, tables, etc.
The Beryl XML GUI library was written to ease the development of graphical user interfaces using Swing on Java. It lets you store user interfaces as XML markup. This will help you avoid unnecessary clutter in your source - Swing code mixed with application logic can become a troublesome and hard to read mess as the application size increases. The library comes with a visual component builder, which makes development a breeze. The most important features are:
he goal of XMLVM is to offer a flexible and extensible cross-compiler toolchain. Instead of cross-compiling on a source code level, XMLVM cross-compiles byte code instructions from Sun Microsystem's virtual machine and Microsoft's Common Language Runtime. The benefit of this approach is that byte code instructions are easier to cross-compile and the difficult parsing of a high-level programming language is left to a regular compiler. In XMLVM, byte code-based programs are represented as XML documents. This allows manipulation and translation of XMLVM-based programs using advanced XML technologies such as XSLT, XQuery, and XPath.
This site is tracking the progress of the XML Processing Model Working Group. It is maintained by Norman Walsh, chair of the WG, but is not otherwise affiliated with the WG or the W3C.
XRules is an XML business rules language that expresses constraints, calculations, interdependencies, and properties that describe and exist among elements and attributes of an XML document. XRules can be used to validate business rules in an XML transaction, attach metadata to the XML Infoset, or add dynamism to XML by using the Dynamic DOM.