I have been working on a small Firefox extension for the reason I guess most people do it: to scratch an itch. Nobody else seemed to have solved this problem, and at some point you then have to just bite the bullet.
The problem I have is that I don’t want to give my email address to anyone, because some of the people I give it to tend to send me spam or somehow get it into the hands of people that send spam. LOTS of spam. On the other hand, I do quite like to receive email, and since almost everyone requires an email address in order to send me the stuff, I had a quandary.
The good news is that there are lots of solutions to this; the bad news is that I can’t remember them when I need to give someone an email address. And so I tend to give them the real one, with the result that I get lots of spam.
The solution I have come up with is called Spam Control, and it’s really very simple. Once installed, it adds a toolbar (which you can disable if you like your screen real estate) and a pop-up menu to Firefox. Whenever an input field has focus, you can click one of the buttons and an email address is added to the field, saving you having to type it or remember it.