This is an Eclipse xml editor with several edition capabilities. The main features concern the interaction with the classes and resources declared in xml (Open class/resource, Create class), similar to the interaction between classes in java editor.
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.
AG101 is a java-based visual XSL editor/debugger built on the Pollo XML editor (pollo.sourceforge.net). It has extensions to a regular expression library. It also has the ability to pipe XSL transforms one to another and store and reuse those pipes.