As a web developer, I understand that many websites need ads to support their income. However, as a user, I understand ads are plain annoying. My father always says he doesn’t mind and likes to at least see them to pretend he’s supporting those ad-supported sites.
Firefox has an amazing addon called AdBlock Plus. This plugin will make your browsing experience quite different. For example, on Facebook with most applications, you’ll see a column of ads along the right side of the screen. With AdBlock Plus enabled, that sidebar will go away. AdBlock Plus saves you bandwidth and makes your browsing experience better and faster.
There are two other add-ons that backup my Firefox installation and favorites. Xmarks makes my life easier at home and at school. Xmarks syncs my bookmarks and passwords between computers. Once you install it, it asks you to make an account and then uploads your bookmarks (and passwords if you’d like) to their secure servers where it keeps your bookmarks encrypted the entire time unless you allow it to use them for other services. The other add-on that makes my Firefox better is a mouth full, Firefox Environment Backup Extension, or FEBE. This add-on will backup just about every aspect of Firefox that you have set or change. I have it backup all of my other add-ons, their settings and also my customized Firefox settings (about:config level settings). It backs up everything at least once a day, I set it back up every 12 hours.
Finally, an add-on that is new to Firefox is new-tab (sadly there isn’t an official site yet). It doesn’t do anything that exciting however it does add some fancy tools to the regular blank tab. For instance, if you copy an address from a web page, and you use ctrl+t to open an new tab, you can easily run that address through Google Maps with one click with the new-tab add-on. It has other uses too, like having quick links to your frequently visited sites and more contextual actions.
Using only a couple add-ons makes Firefox more useful but keeps it fast. There is nothing worse than a useful browser that is slow.