FirePHP enables you to print to your Firebug Console using a simple PHP function call.
What makes FirePHP different?
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..
FIREPHP in drupal (6):
support for fb() function from http://www.firephp.org/. just put fb.php into the devel directory and you can start calling fb() to log information to firebug.
FirePHP – Firebug Extension for AJAX Development
Blogged with the Flock Browser
