eXtensible Programming Language
XPL: XML-based language that will be a 6GL (sixth generation language); open source project, in development.
XML-RPC
A specification and a set of implementations that allow software running on disparate operating systems, running in different environments to make procedure calls via HTTP and XML.
SAX
Official website for SAX, the Simple API for XML, project resources include archived mailing lists, SAX evolution and a download area.