1. Abduction!
Abduction saves your time when it comes on capturing full web page and or just a part of it. Abduction is just a right click away!..
2. Twitbin
With the Twitbin, you can use twitter right from the sidebar of Firefox as you browse the web.
No need to go to twitter.com to send and receive tweets. You can share sites as you browse with just a right click.
3. Video Download Helper
Download helper helps you download and convert Web videos from hundreds of YouTube-like sites.
4. Firebug
For the developers, Firebug is for you, you can edit, debug, and monitor CSS, HTML, and JavaScript live at your Firefox browser.
5. FoxClocks
With FoxClocks, it helps you shows times around the world at the bottom of your browser. You can customize with the time zone you want to display .
Btw, last year my Firefox Add-ons presentation is here and also please checkout Mozilla Blog for the 12 Best Firefox Add-ons of 2012.
