Here is a list some of the XML editors:
1) Stylus Studio 6 (Commercial)
2) Conglomerate (OpenSource)
3) XMetal(Commercial)
4) JEdit (OpenSource)
6) Timelux Xpress
7) Excosoft XML Client
8) Xeena by IBM (commercial)
9) XML Editor - Java based (commercial)
10) Markup Editor 1.1.3 by topologi (commercial)
11) EditML Pro by NETBRYX
12) ElfData XML Editor
13) lucid' xml editor
14) XMLware
15) XML Pro by Vervet Logic
16) xml origin
17) xmloperator
18) Exchanger XML Editor
19) xmlBlueprint XML Editor
20) Visual SlickEdit
21) epcEdit XML/SGML editor
22) Cooktop (Free editor for Windows)
WYSIWYG XML Editors
1) EditiX (Commercial)
2) Authentic by Altova (Commercial)
3) XMLEditor by XMLMind (Commercial)
4) i4i Tagless Editor (Commercial)
5) XMLWriter by Wattle Software(Commercial)
6) eWebEditPro+XML 3.1 by Extron
7) Ultra XML by webxsystems
8) Morphon (Commercial)
9) XMLSpy by Altova
10) Web-based XML editor
11) Syntext Serna (based on XSL-FO) (Win/Lin/Mac)
12) Vex - A Visual Editor for XML
13) Xopus Browser-based WYSIWYG XML editor (XSL+HTML+CSS+JS, XSD) (Commercial)