xul-ext-firebug 1.5.0-2ubuntu1 (amd64 binary) in ubuntu lucid

 Firebug integrates with Iceweasel/Firefox to put a wealth of web development
 tools at your fingertips while you browse. You can edit, debug, and monitor
 CSS, HTML, and JavaScript live in any web page.
 .
 Features:
 .
  * Inspect and edit HTML
  * Tweak CSS to perfection
  * Visualize CSS metrics
  * Monitor network activity
  * Debug and profile JavaScript
  * Quickly find errors
  * Explore the DOM
  * Execute JavaScript on the fly
  * Logging for JavaScript