I want to write a browser plugin that will allow me to load a web page and will sit and monitor the page for any asynchronous updates, and then write the details of those updates to a file. Please point me to the easiest way to accomplish this or to an existing plugin if one exists. Thanks!
Firebug, the de facto standard developer tool for Firefox, includes all of the features you describe, and though logging requests to a file isn't built-in the Omnibug extension appears to support that, or you could build that functionality yourself.