BugMeNot – If you are annoyed by having to fill in forms online just to view free content (the NY Times website is an example), just install this extension, then right-click on the fields in the form, and user-submitted logins will be automatically entered allowing you to get right to the content.
IEView – As much as I’d like to say that I use Firefox for everything, there are the occasional sites that either aren’t functional or don’t look right. In that case, I just right-click anywhere on the page and chose ‘View This Page in IE’ and it will automatically launch Internet Explorer and go directly to the page I was viewing.
Copy Plain Text – Ever try to copy some text from a website into Word or another document and the formatting is all off or all over the place. With this extension, it allows you to highlight text, then right-click and chose ‘Copy as Plain Text’ to have just the information and not all the formatting copied to the clipboard.
Web Developer – For someone like myself who is always tinkering with web development, this extension makes my life so much easier. With drop down menus for CSS formatting and validation services (to name just a couple), this extension must be had for anyone looking to make developing websites easier.
Those are most of my favourites. You can find a few more on my Files page. Let me know if you have any others!