These are the firefox extensions I use today. I hope some of them are as useful for you as they are for me. If you know any extensions I should not have left out or think that one of the below is outdated just leave a comment..

• adblock plus: ad blocker
• cookiesafe: control cookie persmissions from within the statusbar.
• customizegoogle: enhance google search results by adding extra information and remove ads and spam.
• download statusbar: nice download manager
• tagsifter: tag your bookmarks. finally bookmarks become useable..
• update scanner: monitors webpages for updates which still don’t provide rss feeds
• mitm me: bypass the very annoying ssl errors introduced in firefox3 with a single click.
• gtranslate: translates the selected text via google translate
• keyconfig: nice key configuration. Personally I use it to configure the forward and back keys.
• noscript: allows JavaScript, Java, Flash and other plugins to be executed only by web sites of your choice.
• fasterfox: performance and network tweaks for firefox
• unplug: download flash movies easily (for firefox3 there is no “official” but a “modded” version which just alters the version check).
• add n edit cookies: cookie editor that allows you add and edit session and saved cookies
• bugmenot: bypass annoying web registrations with the context menu (input from ).
• refcontrol: control what gets sent as http referer on per-site basis.
• tab mix plus: has a very rich (not to say bloated) feature set. Currently I use the multi row tab feature and the closed tabs icon (which is way better than the default one).
• firebug: edit, debug, and monitor CSS, HTML, and JavaScript live
• safecache: defends against cache-based tracking techniques but is currently only available for firefox2.
• safehistory: defends against visited-link-based tracking techniques but is also only available for firefox2.