WARNING! Download this add-on from LastPass, not from here! Rated 5 out of 5 stars
This add-on is really powerful. It only fails to detect login forms on really dirty coded websites. Now I can use insanely long passwords FOR EACH of my accounts instead of a unique one, so if one of them is compromised, the others accounts are safe. I suggest keeping a backup at home, in case LastPass... dies.
BUT DON'T DOWNLOAD THE OLD VERSION 1.72 HERE! The GUI is really buggy and threatened several times to permanently lose my passwords due to unexplained "rollbacks". You can download the version 1.73 from lastpass.com, this version seems completely stable.
Why the new version isn't here?