Firefox Crosses 2 Billion Add-On Downloads

One of the greatest things about the Firefox browser is that any developer can expand its features and capabilities with a simple add-on. There are add-ons for everything—Twitter, Facebook, Stumbleupon, Digg, feed readers, price comparison, photos, music, and more. Today, every browser supports plug-ins and extensions.

Yesterday, cumulative add-on downloads passed the 2 billion mark. It passed the first billion downloads back in November, 2008. The first billion took three and a half years. The second billion took about 20 months. Many of those are never used again, but a full 150 million add-ons are used every single day at least once.

To celebrate the milestone, Mozilla has put together a collection of the 25 best add-ons. They include StumbleUpon, Glue, Cooliris, Xmarks, Kidzui, Firebug, GreaseMonkey, Adblock Plus, and Destroy the Web (it turns any Web page into a video game). Inexplicably, the list is missing Feedly, the best feed reader of all time.

What else should be on that list?