There are a lot of XML tools available in various states of development. I recently had a chance to evaluate IBM's Visual XML Tools and found them to be quite useful. The Visual XML Tools package consists of several tools:
Visual DTD - a tool for creating and viewing DTDs
Visual XML Transformation - a tool that can help you create a new XML document from existing XML documents. In addition to generating the XSLT script that will transform the source XML documents into the target XML documents, this tool generates a Java class that performs the XML to XML transforms
Visual XML Creation - a tool for creating XML documents from an SQL query
Visual XML Query - a tool for helping you construct an XML query expression
Visual XML Builder - a tool for constructing valid XML document from a DTD
You can read more about these tools at developerWorks. I will keep you all informed as I evaluate other XML tools.