XML Editor: Schema based validation & intellisense, Outlining & Auto Complete. The toolkit also include a graphical XML Schema (XSD) editor, XPath viewer, XML Diff tool, Web Service call composer, and more. [Freeware, Commercial]
A simple yet powerful Graphical XML Schema (XSD) Editor. Detailed properties for each entity, drag & drop, undo etc. Includes many XML tools XSD to HTML, XPath viewer, XSLT editor, XML Sample builder etc [Freeware + Commercial]
Liquid XML Studio 2012 is an advanced XML toolkit and IDE, containing all the tools needed for designing and developing XML applications, including an XML Editor, XML Schema Editor, WSDL Editor, Web Service Tools and much more.