Ganglia is a scalable distributed monitoring system for high-performance computing systems such as clusters and grids. It is based on a hierarchical design targeted at federations of clusters. Ganglia is currently in use on over 500 clusters around the world and has scaled to handle clusters with 2000 nodes.
JaxMe is a Java/XML binding framework based on SAX2. It consists of a set of code generators that read an XML schema and generate code for parsing conformant XML documents into corresponding Java objects, saving those objects into a database or, vice versa, reading such Java objects from a database and converting them into XML. JaxMe supports namespaces, relational databases, and Tamino. JaxMe comes with an integrated application framework and a generator for EJB entity beans with BMP (bean managed persistence).
Jaxup is a Java library that defines an interface to update XML documents, through which clients can work without knowledge of the exact object model that the document uses. The interface is called Updater, and the idea behind it is the same as with Jaxen's Navigator interface. In addition, an implementation of xmldb.org's proposed XUpdate specification is provided. Jaxup supports DOM, JDom, and DOM4J.
NetCrawler is the frontend to a Web crawling system. This command line application will download all of the pages within a domain, and then parse and process all of the relative content (Images, Text, Audio, Video), saving this content within an XML document for later processing. It is definitely alpha quality, but has been used quite extensively.