oh I love this plugins, it really takes all the repetitive work off and works really well. I am using it on both of my browsers FF and Google Chrome.
I would suggest you to use it if you have a lot of usernames and passwords.
I dunno where to post about lastpass so i am posting here as i use lastpass for promoting my site thru SB and ADs.
With LastPass you can store all your passwords at one place. safe and secure. It even fills forms for you and autogenerates passwords. I used it to join 30 SB sites + 20 Article Dirs + 20 Web 2.0 sites...i only have to remember the password to LastPass and then from there its one click autologin to any site. Makes it easy when I have to manually submite articles or bookmark links. You can ensure that lastpass doesnt store your imp passwords like that of your gmail/yahoo mail..its all upto you what you want to store.
Official site: www.lastpass.com
I love LastPass, too, and tell everyone about it. The best thing, and why I prefer it over Roboform, is that you can access your passwords from any computer, as long as you remember your main password. This totally saved my life when my computer completely melted down this past winter.