British English Dictionary R1.19 for Firefox, Thunderbird and SeaMonkey by David Bartlett.
To enable, right-click in a multi-line text box, select "Languages", then "English / United Kingdom".
Select text and it's automatically copied to the clipboard. Also pastes on middle click.
Gives a possibility to create custom toolbarbuttons...
Toggles dictionaries automatically or manually and displays the currently selected one
Add-on for quick bookmarking.
Allows to add or remove links in one click to read it later.
Favicon Restorer brings the website favicons back into the Location Bar in Firefox 14 and above.
This extension also restores the old "blank document" default favicon on new/blank Tabs and Bookmarks.
Get rid of that clumsy context menu, and search the web using up to 100 stylish Drag & DropZones
Browse your bookmarks visually: create, edit, and manage preview images for all your bookmarks. Use bookmark images as a speed dial on newly opened tabs. Quickly transfer bookmarks, links and texts to your mobile phone using QR codes.
Personas Expression adds a lot of customizable visual styles to Personas themes.
You can design your browser more completely.
Will You Become The Stylist Of Browser?
Lets you post photos, videos, mp3s, quotes and links to your Tumblr tumblelogs by dragging and dropping content onto the extension's statusbar icon or by the "Post to my tumblelog" menu items in the content's context menu.