Vex is a CSS-styled XML editor based on the Eclipse platform. It provides a word processor-like interface for document-style XML documents such as DocBook and xhtml.
Catapult is a web based xml content editor for small web sites. The GUI is developed using CSS to be fully customisable and platform independant. The backend file management code is currently implemented in php that allows the user to edit a raw xml file
This is a validating xml editor for creating, edititing an manipulating XML files by a web interface. It is based on open standards like XHTML, JavaScript, DOM and CSS for the client and JavaServlets, JSP for the server.