eXtensible Programming Language
XPL: XML-based language that will be a 6GL (sixth generation language); open source project, in development.
SAX
Official website for SAX, the Simple API for XML, project resources include archived mailing lists, SAX evolution and a download area.
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.