All in one Sidebar (gives a functional sidebar)
GooglePreview (puts preview pics into Google searches)
ScrapBook (allows Notes & complete ripping/archiving of websites for offline viewing)
FireFTP (FTP manager integrated)
Session Manager (save multiple tabs of webpages into 'sessions' <-- core Opera technology)
TabBrowser Preferences (modify tab functionality)
MouseGestures (mouse moves alone can control browsing)
TabMixPlus (makes tab browsing better)
KeyConfig (to remap KB shortcuts)
And I'm adding more daily, like today -- just while writing this, I added TabSwitcher (simpler keyboard control of tab movement), Advanced Dork (Adds in some easy Google adv'd searching), Clippings (stores commonly used text) and KeyConfig extensions.
I finally moved to Firefox w/reluctance after upgrading to Opera 9 from Opera v8.5. I've been a contented Opera user (I really dislike Microsoft IE, which I fondly call Macrosoft Internet Exposer) for years now, and I paid to register Opera a long time ago, but v9, for me, sucked.
Problem --> Opera kicks ass with a lot of beautiful integrated features, like:
- Awesome bookmarks w/metatags
- Great download tool which starts downloading IMMEDIATELY
- Sidebar with bookmarks & useability
- Tabbed browsing -- on steroids
- Integrated search engines
- Zoom controls, style controls, 'fit to page' button, and picture on/off controls
- Remembers 'sessions' so I can start w/a bunch of page tabs loaded
- I never get a virus
So my mission has been to get some of Opera's functionality into Firefox, which I do like, but it's not like Opera in many of Opera's more graceful ways.
So far, I'm getting closer -- but not there yet. :)