Xselerator 

It's got everything an XSLT Editor should have plus a bit more like Intellisense and tag auto-complete! It's also half the price of XMLSpy... so it's great value. A 30 day free trial is available.
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XmlShell - The Ultimate Lightweight XML Editor 

The Ultimate Lightweight XML Editor: 1.True side-by-side XML tree structural view and table/editor/browser views. 2.Grid-like table views to display table-like XML data. 3.Syntax-colored free-form text editor. 4.Intelligent popup list in editor.
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SemanticWorks 

Altova SemanticWorks 2006 is the ground-breaking visual RDF/OWL editor. Visually design Semantic Web instance docs, vocabularies, and ontologies then output the format of your choice. It is the sensible way to put the Semantic Web to work for you.
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Altova Enterprise XML Suite 

The Altova Enterprise XML Suite is a comprehensive XML development toolset that delivers the highest functionality and best product value. It includes Enterprise Editions of XMLSpy, MapForce, StyleVision, and SchemaAgent, plus the new SemanticWorks.
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Altova Professional XML Suite 

The Altova Professional XML Suite is a comprehensive XML development toolset that delivers tremendous functionality at a special price. It includes Professional Editions of XMLSpy, MapForce, StyleVision, and SchemaAgent, plus the new SemanticWorks.
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DiffDog Professional Edition 

Altova DiffDog 2005 Professional Edition is the developer's dedicated differencing utility. This unique XML-aware synchronization tool quickly compares files and directories then highlights differences and merges content via an easy visual interface.
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