The XPath Utility I submitted to the NetBeans Plugin Portal over two months ago has been recently verified against NetBeans 6.7. This makes the plugin now directly available from within the IDE over the Plugin manager (Tools -> Plugins).
One .nbm less to carry with me ;)
I built some time ago a NetBeans plugin which simplifies browsing through large xml documents a bit. Just start typing a XPath expression in the text field of the TopComponent and the result of the (last) xml editor in focus are computed and printed in the textarea below. (You can open the XPath window either by using the context menu on xml files or directly via the window menu)
It uses the JDK's javax.xml.xpath package which means XPath 1.0 support.
it also supports basic auto completion and localized error messages (in other words: XPathExpressionException.getCause().getLocalizedMessage()).
Github project can be found here. Feel free to use it ;)
