Blocks annoying video ads on YouTube, Facebook ads, banners and much more.
Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).
Collector's Note Adblock plus
The first and only download manager/accelerator built inside Firefox!
Collector's Note DownThemall!
IE Tab - an extension from Taiwan, features: Embedding Internet Explorer in tabs of Mozilla/Firefox...
Collector's Note IE Tab
AiOS lets you open various windows as sidebar panels, and quickly switch between them. So it put an end to the window chaos! In addition to bookmarks and history it opens dialogues such as downloads, add-ons and more in the sidebar.
Collector's Note All-in-one Sidebar