Calendar and Date/Time
Shows the calendar week Thunderbird/Lightning calendar's moth and multi-week view.
NoiaButtons No Restart
The 'NoiaButtons' add-on offers cartoonish toolbar button icons (known from Noia themes) for default theme and lightweight themes. Further more lite silver and dark versions of Noia themes are included.
Finds when are people available for a meeting or event via Zonio Freebusy service. Displays freebusy blocks instantly in Invite Attendees window while attendees are being added. Works with both local calendar storage or any calendar provider.
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.
True "Send Later" functionality to schedule the time for sending an email.
Integrates calendars events with Gnome clock applet
Plugin may hang on Fedora.
As a workaround uninstall evolution-ews.
Activity logger (sampled task monitoring) which uses calendar to store user's activities.
It periodically displays window with textbox where user can put description of currently performed tasks. The description is saved in a calendar.
Add Google Tabs to Thunderbird! Services supported: Voice, Calendar, Drive, Docs, Sheets, Slides, Hangouts, Plus, Photos, Contacts, News, Maps, & many more. Need Google Apps? Check out G-Hub Pro: http://www.schiffner.com/index.php/software/g-hub-pro
NirvanaHQ for Thunderbird
Let's show the calendar color on Lightning reminders!
OBM Lightning Calendar and addressbooks connector
Allows two-way access between Remember The Milk and calendar events or todo items.
This addon is now integrated into the new address book CardBook : https://addons.mozilla.org/thunderbird/addon/cardbook/ (and thus it is no longer maintained)
Copy Reminder List To Clipboard No Restart
Provides button to copy the list of current reminders to the clipboard.
Tired to mistakenly press that "Dismiss All" button? Move the Lightining Reminder "Snooze all for" and "Dismiss All" buttons to the LEFT!
... and from version 2.0 you can keep them on the RIGHT, but swapped!
Purge events from Sunbird and Lightning files and thereby cleanes the calendar
Displays tabs which allows quick navigation between time periods in Lightning calendar. All views of calendar are supported. Color of tab texts can be adjusted.
A simple week view for Lightning, as in the print layout.
This add allow to customize the snooze delay when snooze popup appears (lightning required).