Best Add-ons for Firefox and Opera?

[StarKnightX]

With the recent release of Firefox 3 and Opera 9.5 , I was wondering what good and recommended extensions , add-ons , widgets and plug-ins there are for these two browsers? I would also be open to mentions for IE and Safari but I don't think either of them support extensions , nor do most people recommend using them.

The only recent thread I found that seemed relevant to the topic was here:
http://www.cheapassgamer.com/forums/showthread.php?t=58266&highlight=extensions

but I thought with it being over a year old , that things might have changed by now. I just want to try and make my web browsing experience as smooth and productive as possible.

 

[joldko]

simaquarium

 

[Rusty Ghia]

Adblock Plus and NoScript.

 

[YodaEXE]

Greasemonkey!

 

[Chris S]

Foxmarks

 

[n25philly]

oldbar makes FF3 actually usable

 

[plasticbathmonki]

Noscript

 

[metaly]

What I have installed for general use:

AdBlock Plus
Delicious Bookmarks
Download Statusbar - unobtrusive download manager
Fission - puts the loading progress bar in the address bar, like in Safari

For Web dev stuff:

Autofill Forms
Firebug - Indispensable. I wish this had existed 10 years ago.
IE Tab - Runs IE's rendering engine in a FF tab. It still sucks and is totally buggy, but at least it's in the same window!
Unicode Input Tool/Converter
Web Developer

 

[eswat]

Opera... addons? What? ;P

For Firefox:
Adblock Plus
Delicious Bookmarks
PicLens