Although this section is called "Importing and Exporting", what most people really want is a live sync of all of their calendar data in one place. No one wants to have to periodically go through the manual process of importing and exporting events across different systems.
localendar supports this type of dynamic, automatic merging using the popular (and open) iCalendar format.
Understanding localendar support of the iCalendar format
Exporting to Google Calendar
Exporting to Microsoft Outlook
Exporting to Yahoo Calendar
Importing iCalendar into your localendar
Importing from Google Calendar into localendar
Importing from Facebook into localendar
Importing from Yahoo Calendar into localendar
Other Export/Import Options
Exporting localendar to a CSV file
Importing a CSV into localendar
localendar and the Wyncs browser plug-in