Some of the nice little addons that are my personal favorite are:
- Firefox Universal Uploader (fireuploader) 0.4.1 - Upload to a wide list of web-sites, including Google Docs.
- Gmail Checker/Gmail Notifier - Run your gmail in your browser bar, also has the ability to check multiple inboxes.
- PowerBar - Not the best looking bar, but is big and has shortcuts for all Google features as well as a ton of other things.
- Stumble-Upon - Browse websites and discover new things.
- Better Gmail - Faster and better gmail in your browser.
- Xoopit - Stores images, videos and documents that you receive in emails.