PUBLIC MARKS from decembre with tags calendar & synchroniser

With CalDAV support in Google Calendar, you'll be able to view and edit your Google Calendar events directly in other calendar applications, such as Apple iCal or Mozilla Sunbird. Any changes you make in other calendar applications will automatically appear in Google Calendar the next time you sign in (and vice versa). If you use other calendar applications while offline, changes you make will be saved and updated in Google Calendar when you get back online.