XML Copy Editor - XML Copy Editor is a fast, free, validating XML editor.
Stylus Studio - Stylus Studio® 2010 XML Enterprise Suite is an advanced XML Integrated Development Environment...
EditiX - EditiX is a quality Open Source XML Editor and XSLT Editor for Windows, Mac OS X and Linux. Test for Free with our 30-day Trial !
XMLable - XMLable is an online toolbox designed for working with XML, offering tools such as a formatter, validator, comparator, generator, XPath tester, XSD generator, and XSL transformation.
Liquid Studio - XML Tools Provider: XML Studio - Graphical XML Schema Editor.
XML ValidatorBuddy - Makes working with XML as fast and convenient as never before.