ThreadKey Requires Restart
Strike the 'T' key to sort messages by thread, strike the 'U' key to sort them unthreaded again, just like the 'G' key switches to Grouped By Sort view
RC Print Requires Restart
Adds a "Print" option to the Right-Click context menu.
Darkens the background of the page
Stylish Tools Requires Restart
Quicker access to several Stylish features through a toolbar button and/or keyboard shortcuts. Available for Firefox, Thunderbird, and SeaMonkey
A button to be able to open the profile folder, along with two buttons to create profiles, and also switch the current profile.
Select link text with easy mouse gestures.
Open With Opera sends pages, links, tabs and images from Mozilla Firefox to Opera.
Enhanced Priority Display Requires Restart
Enhanced thread pane display of message priorities.
InspectorWidget Requires Restart
Adds toolbar button and context menus for invoking the DOM Inspector (DOMi) for either chrome or content elements.
CheckBoxMate Lefedor Edition Requires Restart
Check multiple checkboxes by drawing a rectangle around them. FF6 version.
I've made this version since i did need it for use with RTM,
Single Key Tab Switch Requires Restart
Single Key Tab Switch provides configurable single hotkeys for switching tabs, like the 'Single-key shortcuts' feature of the Opera browser.
HTML5 Loop Requires Restart
Loop HTML5 Video and Music.
Link Status Redux Requires Restart
Shows an indicator on the status bar in front of the link address when the mouse cursor is over a link to a page you have bookmarked or visited before.
HashColouredTabs+ Requires Restart
Improves tab identification by providing a small colored icon for any site which doesn't have its own 'site icon'.
★ 'favicon' now also shown in history and bookmarks ★
Stylish-Custom Requires Restart
custom additions to Stylish extension
Reopens the last closed tab.
Reload page without using content stored in the browser cache to make sure you get any updates.
GNOMErunner Options Requires Restart
Allows to customize GNOMErunner theme
Prevent duplicate tabs. Allow only one tab for a url. If you click a link that is already opened in a tab, then existing tab would be focused instead of opening a new tab. This works even across firefox windows.