This is great for a power user, and hopefully for mom too. To me, it's the same power-to-the-people type of idea where a personal server is advocated rather than Facebook; in this case, it's your browser rather than OAuth. The only plug-in that keeps me on Firefox rather than switching to Chrome is http://www.andyhalford.com/syncplaces/ because I can sync my passwords across Firefox installations on multiple computer…
for me, the only thing keeping me off of chrome is that it has no "master password" concept to protect stored passwords. on firefox, i use the master password timeout extension ( https://addons.mozilla.org/en-US/firefox/addon/1275 ) so it has to be re-entered after a few minutes of not using it.
Set a password on your OS account.