Don't like right-clicking? Use this restartless add-on to toggle your App Tabs with a double-click!
F1 has been replaced with Firefox Share (alpha) at https://addons.mozilla.org/en-US/firefox/addon/firefox-share-alpha/
Add useful extra features to Google Reader, like feed favicons, inline article previews, and unread counts in your browser tab with Better GReader.
Find stuff instantly from a dashboard that appears over a full-window browsing experience.
A lightweight ruler to measure web page elements.