Firefox plugins
 

Cooliris was pointed out in another thread. But I found it to be too intrusive.

However, I do find these two useful:

Google Browser Sync - keeps my work and home bookmarks in sync. There are other synchronizer plugins out there, but I already had the google id from having gmail.

IE Tab - There are some sites that are strictly tailored for Internet Explorer. But I prefer Firefox in all other things. This plugin uses the IE component to embed an ie browser in your Firefox tab. Means I don't ever have to use IE now.

Any other useful ones out there?

Ad Block Plus and Accuweather

2nded Bullitt.

The flash block thingie?

FoxyTunes

Batch Download

Duplicate Tab

Gmail Space

Image Toolbar

Pop-Up Master

Snap Links

Unhide Passwords

Adblock Plus is awesome.

FireFTP is another good one.

I mentioned Flashblock in another thread. I don't block all ads but I do block Flash and selectively let it through on places like YouTube.

ShowIP
Web Developer
Total Validator
MeasureIt
LinkChecker
Colorzilla

I've used these from various troubleshooting and web design activities.

I also use

Download Statusbar - put download status in your status bar where it belongs.

ChromaTabs: color your tabs according to what site they're on. All my Cellar tags are red, all my Gmail tags are blue, etc. makes it easy to remember where you are.

Gmail Notifier: number of unread Gmail msgs in your status bar.

I can spend hours using StumbleUpon.

These are the ones I use:

NoScript
AdBlock Plus
IETab
ChatZilla
FoxyTunes
Gmail S/MIME
VideoDownloader
Verisign EV Green Bar Extension

There's more that I have used in the past (CustomizeGoogle), but I don't because of issues.

Adblock Plus
del.icio.us
DownThemAll!
Faster Fox
Forecast Fox
Google Notebook
IE tab

Download Statusbar
DownThemAll!
Flashblock
Gmail Notifier
GreaseMonkey (There's a Greasemonkey script that makes linked Flickr pics in bbcode)
ImageZoom
Tab Mix Plus

Even before going to FF, I had accumulated a setup that keeps my machine sparkling clean...

Zone Alarm as a firewall - Free
AVG Antivirus - Free
Pestpatrol - I paid for it once

I ran a full scan w/Pest Patrol followed by an Adaware scan, and came up w/nothing but a few cookies...this after about five months of daily hard use. I'm happy.

I run AVG and ZA, along with Spyboy S&D, and in 2 years I have had no problems.

Another useful plugin - Drag and drop upload for gmail.

https://addons.mozilla.org/en-US/firefox/addon/2190