With FirePath you can:

• Edit XPath expressions and CSS3 selectors.
• Evaluate the expression on HTML or any XML documents.
• Display the result of evaluations in a Firebug-like DOM tree.
• Highlight the results directly on the document displayed by Firefox (works only with HTML documents).
• Generate an XPath expression or a CSS selector for an element by right clicking on it and selecting "Inspect in FirePath" in the context menu.
• Define the evaluation context of an XPath expression or CSS3 selector.
• Choose the document in which to evaluate the XPath expression or CSS3 selector (only applicable for HTML documents with frames or iframes).

The last version of FirePath can be found here: https://addons.mozilla.org/firefox/addon/11900/

If you need help please use the discussion group here: http://groups.google.com/group/firepath

If you think you found a bug please create a new issue here: https://github.com/pierretholence/firepath/issues