ColorfulTabs – Having too many tabs open can lead to a lot of confusion, but this extension will assign your tabs different colors so you can tell them apart easier.
Adblock Plus – The popular, yet controversial extension has been updated to work with the latest version of the browser, and it’s still doing what it does best: blocking ads.

ChatZilla – Add an IRC client to your browser so you can chat in it directly without having to open any other applications.

ColorZilla – An extremely handy tool for Web developers to let them see the RGB and Hex values of any color on a Web page.

Del.icio.us Toolbar – Quickly add bookmarks to your Del.icio.us account, edit tags and access your account.