You can arbitrarily inject javascript on any page after launch. Here's how to do it in Safari http://www.youtube.com/watch?v=34D7IR7lNHc http://www.youtube.com

You can arbitrarily inject javascript on any page after launch. Here's how to do it in Safari http://www.youtube.com/watch?v=34D7IR7lNHc http://www.youtube.com/watch?v=34D7IR7lNHc Chrome: View > Developer > Javascript Console Firefox: Install the firebug extension, which does autocompletion and makes developing much more fun. Not sure if this still works in Firefox 4