This post is a just a reference for me in case I have to re-install firefox I would have blue print of all the extensions I use. Of course you also may be able to discover some extensions through it.
1. Quick Drag
2. Hide Menu
3. Hide Caption
4. Switch Proxy
5. Paste and Go
6. Undo Close Tab
7. All In One Gestures
UPDATE: I created an add-on collection for the above here