The first and only download manager/accelerator built inside Firefox!
Lightbeam is a Firefox add-on that enables you to see the first and third party sites you interact with on the Web. Using interactive visualizations, Lightbeam shows you the relationships between these third parties and the sites you visit.
Multiple account (or label) Gmail notifier (without storing passwords)
Evernote Clearly makes blog posts, articles and webpages clean and easy to read. Save them to Evernote to read anywhere.
The greatest user script engine on the Internet (a fork of Greasemonkey).
NewTongWenTang is a tool to switch display Chinese content between traditional and simplified glyphs (中文繁簡體互轉工具)
Integrate your Google Calendar with Firefox in a simple way.
No need extra login!!
telnet client extension specifically designed for BBS browsing.
It support mouse browsing and FireGestures script.