If you use Firefox, I bet you already know Firebug extension. This is irreplaceable tool for web development. But there is also FirePHP extension, which provides possibility to log into Firebug console from PHP scripts. This is very convenient way for debugging process, because logs are independent from application output.

He shows the integration you can do with the Zend Framework's Zend_Log component to write basic messages and the Zend_Wildfire component to write tabular data back to your browser's console with two snippets of code.