- Open your contacts, calendars or tasks in the webapp.
- Click the "cogwheel" icon behind the address book, calendar or task list that you want to export (you may have to unhide the left task bar, if it's currently hidden).
- Click the "Download" button.
That's it, your browser will download the respective vCard or iCalendar file. Repeat these steps for all address books, calendars or task lists that you want to export.