No this is not a list of "THE BEST EVER" extensions ... I am so sick of those. I am just going to list the ones I use and never set up a PC without. After trying several I have come to be comfortable with the following list.

Adblock Plus

Gets rid of annoying ads

Adblock Filterset.G Updater

Synchronizes Adblock with Filterset.G

CustomizeGoogle

Remove ads, Google tracking and much more!

DownThemAll!

Mass Downloader

Foxmarks

Synchronize bookmarks between machines

Greasemonkey

User Script Manager

IE Tab

Use embedded IE engine within Firefox

MinimizeToTray

Keeps Firefox running in memory, in taskbar

No Squint

Increases small text on websites and keeps the settings

StumbleUpon Toolbar

Self Explanatory - I customize to use as little space possible

Of course I am always trying new ones as they come out and if I ever get time would like to create my own.

How about everyone else? What are some of your favorite extensions and why? I look forward to your feedback.