Firefox extensions that rock my world

You've probably read countless blog entries elsewhere on the top must-have Firefox extensions. Well here's what rocks my world:

• Google Toolbar: the spell checker is good enough a reason
  
• MeasureIt: a ruler to measure any web element's height & width
  
• ColorZilla: stop picking colours out of screenshots in Photoshop - this one's a gem
  
• Dummy Lipsum: all the blind text you'll ever need for testing web apps
  
• Live HTTP Headers: excellent for debugging your web apps http traffic
  
• SoThink SWF Catcher: great app to grab Flash (swf) movies of any webpage
  
• Web Developer: a must have for any web developer
  
• Screen grab!: capture an entire webpage and stop piecing it together in Photoshop