XMLSpy Professional Edition
Altova XMLSpy 2006 Professional Edition is the industry leading XML development environment, providing intuitive editing views and powerful XML utilities to model, edit, transform, and debug XML technologies quickly and easily. XMLSpy 2006 Professional Edition includes the world's leading XML... Additionally, support for a schema-aware XQuery processor and a robust XQuery debugger allow intelligent querying of XML data while working with XML and databases. ... Altova XMLSpy 2006 Professional Edition is for the professional developer working with XML, XSLT, XPath, XQuery, and XML Schema.
http://www3.altova.com/download/2006/XMLSpyProf2006.exe - 16Mb - Download - Screenshot

XMLSpy Enterprise Edition
Altova XMLSpy 2006 Enterprise Edition is the industry standard XML development environment for modeling, editing, debugging, and transforming all XML-related technologies, then automatically generating runtime code from schemas in multiple programming languages. ... A schema-aware XQuery processor and a robust XQuery debugger allow intelligent querying of XML data while working with XML and databases. ... XMLSpy Enterprise Edition offers advanced WSDL and SOAP capabilities, including WSDL file visualization, editing, and validation, SOAP request/response activities, and a SOAP debugger.
http://www3.altova.com/download/2006/XMLSpyEnt2006.exe - 16Mb - Download - Screenshot

oXygen XML Editor and XSLT Debugger
Oxygen is a multi-platform XML Editor, XSLT/XQuery Debugger and Profiler with full Unicode support. It offers a powerful code insight that can follow a DTD, Relax NG or an XML Schema or even can learn the structure from a partial edited document. XML and XSL documents can be easily associated... Oxygen validates XML, XSL, XQUERY, FO, XSD, RNG, RNC,NRL, DTD, Schematron, WSDL and CSS content, reporting errors with description and line number information and marking them in the document when validate as you type is enabled.
http://www.oxygenxml.com/InstData/Windows/NoVM/oxygen.exe - 16Mb - Download - Screenshot