From Open Source Ecology
- HTTPS Everywhere - encrypts your communications with many major websites, making your browsing more secure
- Scrapbook - save web pages offline and organize them. Useful when on the way without internet connection.
- Tree Style Tab - moves the tabs on the left side. Much easier to navigate.
- Restart Firefox - adds File->Restart.
- Flash Aid - fixes Adobe Flash problems.
- Rss Icon in Awesomebar - adds the rss icon
- Video DownloadHelper - download videos from youtube and convert them.
- Shareaholic - share interesting links using Facebook, Twitter, Google Mail, Reader, Bookmarks, Evernote, Bitly, StumbleUpon, and more.
- Boomerang for Gmail - Send an email later, follow up reminders, remind you if you don't hear back.
- Wired-Marker - highlight website texts, you can define your own shortcut from the properties of every color.