I currently use Sunbird, and I like it for the most part, but its support is being dropped and it doesn't integrate with Unity. I'm looking for a calendar or personal organizer program which would run in the background as an app in the Unity system tray, and notify me of upcoming events without having to be explicitly opened.
However, I would rather not have this tethered to a mail client. An easy transition for data from Sunbird would be a bonus. Suggestions?