I've been using Firefox as an internet browser for a while now. I've stumbled on several Add-ons that have made my life easier or fixed problems, namely:
New Tab Homepage
This takes you to your home page when you open a new tab. It would seem to be something Firefox should already have, but OK.
Sidebar Bookmark Selector
The default bookmark setup is a bit busy/cluttered for my taste. This add-on allowed me to hide folders/items that I don't use but can't delete.
I recently discovered this work-around to make it easier to switch gmail accounts without logging out and logging back in each time. It seems a bit glitch-y but so far I'm keeping it.
If you know of other useful add-ons, feel free to submit a comment! I love hearing from people :)