Tab Mix Plus enhances Firefox's tab browsing capabilities. It includes such features as duplicating tabs, controlling tab focus, tab clicking options, undo closed tabs and windows, plus much more. It also includes a full-featured session manager.
A customizable mouse gestures extension which enables to execute various commands and user scripts with six types of gestures.
NoSquint allows you to adjust the text-only and full-page (both text and images) zoom levels as well as color settings both globally (for all sites) and per site.
IE Tab + is an enhanced version of IE Tab. It supports FF 3.5 or greater, integrates IE Tab with Adblock Plus in the IE Tab engine, and synchronizes cookies between IE and Firefox. You can easily import settings from the original IE Tab into IE Tab +
Make any pages' search functionality available in the Search Bar (or "search box")...
Scrolls the page smoothly when scrolling the mouse wheel (or keyboard arrows if enabled).
The greatest user script engine on the Internet (a fork of Greasemonkey).
Enables automatic replay of a YouTube video or watching a part of it again and again...
AutoPager automatically loads next pages when you reach the end of a page. It works on a ton of sites,Google,Yahoo..
It works well with most other add-ons adblock plus, WOT and most of the greasemonkey scripts.
You can also try AutoPagerLite.
NewTongWenTang is a tool to switch display Chinese content between traditional and simplified glyphs (中文繁簡體互轉工具)
Select a number of links with a rectangle and open them all in new tabs in the same or a new window(s), download them or copy them to the clipboard. You can also lasso checkboxes to quickly check or uncheck them.