The XML schema tools available in the NetBeans Enterprise Pack 5.5  
Early Access release allow you to visualize and edit XML schemas. The  
XML schema tools focus on complex information display and real-world  
use issues (for example, scalable visualization and editing of  
massive XML schemas). In addition, the XML schema tools reduce the  
complexity of creating and editing XML schemas, thus allowing someone  
who is not a schema expert to create and modify XML schema and other  
XML documents. Using the XML schema tools, you can reference external  
schemas and run advanced queries in the Analysis view.

Using XML schema functionality, you can:

   * Visualize and edit an XML schema in a scalable fashion using the  
Schema view
   * Edit a schema via an abstract instance view which provides an  
editable visualization of the instance document structure
   * Query and Visualize the Schema
   * Perform refactoring across XML Schema, WSDL, and BPEL

Netbeans Enterprise Pack Download: http://www.netbeans.org/products/ 
enterprise
Netbeans XML project: http://xml.netbeans.org