This is my latest Firefox extension I'm working on. There's been too many times when I've lost a post on a message board, or an email, or something similar because my browser crashed. This Firefox keylogger will record that, so I can retrieve the lost text. I added the "Minimum string size to log" so it won't save really short text--like passwords.
Official Firefox add-On page: https://addons.mozilla.org/en-US/firefox/addon/8261
Quick-link to download: http://stormhorse.com/keylogger-1.1-fx.xpi