foxulet/fireNode ยท GitHub
https://github.com/foxulet/fireNode
A simple implementation of Firebug's Wildfire protocol for node.js
FirePHP - Firebug Extension for AJAX Development
http://www.firephp.org
"All data is sent via a set of X-FirePHP-Data response headers. This means that the debugging data will not interfere with the content on your page. Thus FirePHP is ideally suited for AJAX development where clean JSON or XML responses are required."