Most Popular for ITM Clients
:: Adblock Plus
:: Better Privacy
:: Bookmarking
:: Colorful Tabs
:: deskCut
:: Download Status Bar
:: Firefox Extension Backup
:: Forecastfox
:: Google Toolbar
:: IE Tab
:: Morning Coffee
:: PDF Download
:: Screen Grab
:: SearchPreview
:: Security Check
:: Send Text Messages
:: Site Advisor
:: Video DownloadHelper

Themes
Themes change the look and feel of Firefox Navigational bar. It's normally gray. This makes it more fun and to your liking. They're also known as "Skins." Download these, re-start firefox, and manage them by clicking on "Tools, Add-Ons, Themes."

For Pink Fanatics
:: Pink Pack 1.9
:: AvantGarde Rosepetal

Just For Fun
:: Grocery List Generator
:: PONG!
:: Price Blink
:: StumbleUpon

In Testing
:: All in One Sidebar
:: Download Embedded
:: Firefox Showcase
:: Foxmarks
:: Gmail Space
:: Gmail Manager
:: Gmail Skins
:: Hebrew Calendar
:: Image Assistant
:: Kid Friendly Environment
:: MozBackup
:: Performancing
:: Reveal
:: VideoDownloader

Social Networking
:: Facebook Photo Album
:: Downloader
:: Facebook Video
:: Downloader
:: Power Twitter

Others of Interest
:: Add N Edit Cookies
:: Autofill
:: Biet-O-Zilla
:: Blogger Web Comments 
:: Bookmark All
:: Download Manager Tweak
:: Fare Watcher
:: Flash Block
:: FoxyTunes
:: Googlebar Lite
:: Google Extensions
:: Googlepedia
:: Google Safe Browsing
:: Google Send to Phone
:: Google Suggest
:: Groowe Search Toolbar
:: IE View
:: Kimba Kano
:: Mapit!
:: Master Password Reset
:: Mr Tech Local Install
:: QuickTabPrefToggle
:: Roboform Extension
:: RSS Panel
:: Sage
:: Site Advisor
:: Smiley Xtra
:: SpellBound
:: StockTicker
:: Tab Mix Plus
:: TinyUrl Creator
:: Toolbar Buttons
:: Webmail Compose
:: Wizz RSS News Reader
:: Yahoo Toolbar

Google Chrome Extensions
Google pulls ahead and develops extensions for it's cool browser Chrome.  Here is the official page of extensions.

Below - our favorites:
:: **** AdBlock
:: AdThwart
:: Brizzly
:: Chromey Calculator
:: Click&Clean
:: Docs PDF/PowerPoint
   Viewer
:: ****Downloads
:: Facebook Disconnect
:: FastestChrome
:: Flixster Movies
:: ****Forecastfox Weather
:: Google Chrome to Phone
:: ****Google Contacts
:: Google Mail Checker
:: Google Translate
:: IE Tab
:: IMDB
::****Invisible Hand
:: Last.FM Music Player
:: NewsReader
:: Picnik
:: ****Price Blink
:: ****Screen Capture
:: VerticleTabs
:: Web Page Screen Shot
:: Window Close Protector
:: Wise Stamp
:: Xmarks Bookmarks Sync
:: Xmarks Thumbnails
:: You Tube Music Lyrics