Well, complicated heading, I suppose.
I am thinking of a workaround for a big web annoyance: having just finished entering a larger text into a web form (e.g. the body of an email or an entry in a forum) than hitting the right button, but having lost connection or the session, or hitting the wrong button and leaving the current page -> your entry is lost.
I usually do Ctrl-A Ctrl-C to have a backup of my entry before I continue navigating, but I think that could be done automatically: copying the contents of the text field having the last focus. Maybe this is an idea for a Firefox plugin?