Tategaki Requires Restart
Tategaki allows vertical writing-mode on mail compose window.
Text2Link Requires Restart
Text2Link is a simple and easy-to-use way to copy the text of a link, or to open URLs and send emails to addresses not marked-up as HTML links.
Theme Font & Size Changer lets you change the global font size and font family used for the user interface in Firefox. Design your browser with your favorite font.
ToggleDocumentColors_ Requires Restart
Adds a toolbar button and keyboard shortcut to switch between the default page colors and user-defined colors.
Firefox shortcut: Control-Shift-C
SeaMonkey shortcut: Control-K
Adds toolbar buttons for each restartless add-on (including user scripts and plugins) to toggle its enabled state.
This extension enables true full screen mode in SeaMonkey for HTML5 video players, slide-shows, etc. and also for full screen invoked manually with the F11 key.
Block advertisement and access to adult sites
WebPG for Mozilla Requires Restart
An extension which provides GnuPG/GPG/PGP related functions to Moizilla Firefox, Thunderbird and Seamonkey
Xclear Requires Restart
Safari-like icons in the URL, search and find fields to clear their contents.
xSidebar Requires Restart Featured
Firefox style sidebars for SeaMonkey...
Watch videos anywhere in cinema mode without leaving the website you're on.
YouTube Video Player Pop Out lets you pop out YouTube videos so that you can watch YouTube videos while you surf.
Want to change from one language to another? Zing! and the locale is switched.
Zorcher Requires Restart
Selecting a small text on the page do not need to copy it into the search bar of your browser or search engine. Just press the right mouse button and select the search service from the available list.