Carol's Top Ten Firefox add-ons

I recently started using Firefox again as my default browser. One of the big reasons I favor it over MSIE is for the nifty add-ons. Here are my top ten favorite add-ons and built-in features:

1. Undo Last Closed Tab - Brilliant and self-explanatory. Perhaps the #1 reason I made the switch.
   
2. AdBlock Plus - Instead of ads on websites, I see pure white bliss. Pages load a lot faster too!
   
3. Search Bar - has a pulldown where you can choose to search Google, Amazon, Wikipedia, or a host of other common choices. Customizable. I use those three a lot!
   
4. Fast Dial - Maybe this is just a visual way to sort your favorite bookmarks, but I love it.
   
5. Foxmarks - Automatically sync your Firefox bookmarks on any computer that you own or use (also syncs Fast Dial)
6. Password storage - I just like that you can wait to answer the "would you like me to remember this password" question until you know for sure you typed the right one! FF asks the question in a drop down bar instead of a pop-up window, and you don't have to respond right away in order to proceed.
   
7. ForecastFox - Tiny, tidy current weather and forecast, subtly in your status bar. It would be even more perfect if it could detect what city I'm in when my laptop goes on a trip!
   
8. Yahoo Mail Notifier - the only reason I ever used the bulky Yahoo toolbar, this version takes only about a quarter-inch of real estate on your status bar.
   
9. Google Calendar Sync - whether or not you actively use Google Calendar, did you know you can use it to keep your Outlook calendars automatically synced across multiple computers? (this one isn't Firefox-specific, I'll admit)
   
10. Prompt/Ability to save all current tabs when you shut the program down.

What did I miss? Tell me your favorite features in the comment section...