HTML & XHTML
CSS - Cascading Style Sheets
XML - Extensible Markup Language
Java™ - java.sun.com
JDOM A document object model for Java. It provides a document representation for reading, manipulation, and writing. The API is optimized for Java. It's an alternative to DOM and SAX, although it integrates with both of them.
dom4j A document object model for Java. dom4j is an Open Source XML framework. It allows you to read, write, navigate, create and modify XML documents. dom4j integrates with DOM and SAX and support XPath.