Mozilla Lightning – Calendar Addon for Thunderbird
Mozilla Thunderbird is a great email client but it lacks of calendar functionality (scheduling, tasts, etc) like Microsoft Outlook. Lightning is a free calendar extension that tightly integrated with Thunderbird.
The latest version is Lightning 0.5 (download).
Image: Mozilla Lightning calendar
I installed Lightning 0.5 for Thunderbird on Mac. It runs smoothly and automatically import iCal (can import Google calendar with addon). Lightning adds a small calendar view and list of agenda, to-do, and calendars at the bottom of Thunderbird sidebar. It allows seamless switching between email accounts and calendar.
Image: Editing event in Mozilla Lightning calendar
Lightning is a perfect calendar add-on for Thunderbird. It is still in early development stage. More features have planned for future releases, such as email-to-task linkage, address book integration, device synchronization, etc.
My two cents
As a Thunderbird fan, I am glad to know a calendar for Thunderbird is under active development. I had minor problem with Lightning as it takes 2-3 seconds to open event editing window. I believe it will be improved and am looking forward for Lightning 1.0.