Rated 5 out of 5 stars
LastPass is the single most awesome service there is. You can secure all your passwords with it and forget them entirely. You can use it from anywhere, anytime, on any browser or OS, even without the add-on itself. You can use it to store passwords, e-mails, credit card data, your computer's passwords (in case you forget them, so you could login into your LastPass account from elsewhere and retrieve them), and any other piece of text you need (via Secure Notes). It's secure, reliable, easy to use and automated.
Personally, I use LastPass to store all of my Internet passwords (including other services' like Xmarks and ReadItLater), my BIOS passwords, several of my 32-symbol TrueCrypt passwords (all generated by LastPass), and my Windows and Linux login passwords, across Firefox and Chrome. I just can't imagine browsing without it.