Lightning Requires Restart Featured
Organize your schedule and life's important events in a calendar that's fully integrated with your Thunderbird email. Manage multiple calendars, create your daily to do list, invite friends to events, and subscribe to public calendars.
ReminderFox Requires Restart Featured
ReminderFox displays and manages lists of reminders and ToDo's. ReminderFox makes sure you remember all of your important dates via easy-to-use lists, alerts, and alarms, right in your browser without the need for a separate calendar program.
xSidebar Requires Restart Featured
Firefox style sidebars for SeaMonkey...
Enigmail Requires Restart Featured
OpenPGP message encryption and authentication for Thunderbird and SeaMonkey.
NewsFox Requires Restart Featured
NewsFox is an efficient 3-pane(email) style Atom/RSS feed reader.
FlashGot Mass Downloader Requires Restart Featured
Download all the links, movies and audio clips of a page at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers.
The first and only download manager/accelerator built inside Firefox!