Vastly improves my web-browsing experiences Rated 5 out of 5 stars
I've been using for this so long that I can barely remember using firefox without it... However, when I was visiting my mum recently I added Ablock Plus to firefox for her, at her request. I'd been telling her how fantastic it was to be free of endless irritating online adverts and I was impressed that Adblock Plus even cuts out the ad-breaks when you're watching catch-up TV online. If, like me, you want ZERO intrusion from online advertisements then make sure you go to Add-ons Manager, click on "options" for Adblock Plus and then click the "Filter preferences..." button. Near the bottom of the window that opens there's an "Allow some non-intrusive advertising" option. Just un-tick that box!
Sorry if that sounds patronising to some/most people but I've just had one those hour-long, "Something's gone wrong with my computer" type phonecalls from my mum, so I'm still in 'simple step-by-step instructions' mode...!
Oh and by the way: the Ghostery add-on compliments Adblock Plus perfectly, in my opinion.