My Firefox Extensions currently installed:

Many of my extensions serve to quickly find text information, for example GooglebarLight, SearchPreview or GoogleEnhancer. There are also a lot of addons that I need for web- and addon-development. I prefer straight functionality over other features. Skin and visual elements have to be as small as possible. And for sure, I always have my own addons installed to get notified when something is broken. You probably find that some of the other addons are quite old and version-locked (un-installable), but if you are an experienced user, then you will know that many of them still are fully compatible. Fortunately it is easy to unlock them and you even can automate that process with the NightlyTesterTools addon.

• Aardvark
• Active Stop Button
• Adblock Plus
• Add Bookmark Here ²
• All-in-One Sidebar
• AskForSanitize
• BabelFish
• BetterCache
• BetterPrivacy
• Bookmarks UI Consolidator
• CacheViewer
• Classic Compact Options
• Clear Cache Button
• Clipboard-Save-As
• Console²
• Context Bookmarks
• Copy Link Text
• Copy URL +
• Dictionary Switcher
• Disablemenu
• EbaySearchPictures
• Extension List Dumper
• File Title
• Firebug
• Flagfox
• Full Reload Button
• German Dictionary 2.0
• Go Parent Folder
• Googlebar Lite
• GoogleEnhancer
• Greasemonkey
• Highlighter
• Image Zoom
• JSView
• Lazarus: Form Recovery
• Linkification
• Manage Folders
• Menu Editor
• MIME Edit
• MinimizeToTray revived (MinTrayR)
• MultirowBookmarksToolbar
• Nightly Tester Tools
• Old Add Bookmark Behavior
• Old Location Bar
• Organize Status Bar
• Paste and Go 2
• Perspectives
• PrefButtons Plus
• QuickPageZoom
• RefControl
• RightToClick
• Scroll Search Engines
• Searchbar Autocomplete Order
• SearchPreview
• SearchWP
• Show my Password
• ShowIP
• Split Pannel
• StayInOnlineMode
• Stop Autoplay
• Tab Mix Plus
• Text Area Resizer and Mover
• Toolbar Buttons
• Undo Bookmarks Menu
• United States English Dictionary
• UnMHT
• Update Scanner
• User Agent Switcher

Still here?
Here comes a small bonus, some addons that I consider as very useful - but unfortunately not well maintained by their owners. I felt they need some care....

Miscellaneous addon goodies, modded or improved compared to the official versions:
- Installation: StopAutoPlay addon - the better FlashBlock --- Version 0.7.7nc (bugfix, it sometimes failed to block Flash)
- Installation: DictionarySwitcher addon --- Version 1.2nc (fixed: often failed with auto-detection)
- Installation: UserAgentSwitcher addon --- Version 0.7.2 (made useragent sticky over sessions, won't update!)
- Installation: Highlighter addon --- Version 0.1.5

Important: Addon installations need script & cookies enabled!