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).
Download all the links, movies and audio clips of a page at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers.
Japanese to English/German/French/Russian dictionary. Just hover the mouse on top of a word, and a popup appears. Automatically de-inflects verbs and adjectives. Detailed kanji view...
Add useful extra features to Gmail, like hierarchical labels, an unread message icon on your browser tab, file attachment icons, and more.
Convert text URLs and links to images into thumbnails.
Note from Mozilla: This add-on has been discontinued. Try Google Minimalist instead.
CustomizeGoogle enhances Google by adding information and removing unwanted information.
Characterizer allows you to practice Japanese or Chinese characters while you read English (or other languages) by replacing the first letter (or entire word) with a character. For example, the word read might appear as 読ead.
Add useful extra features to Google Reader, like feed favicons, inline article previews, and unread counts in your browser tab with Better GReader.
Collections are groups of related add-ons that anyone can create and share.Explore Collections