Online Calendar

Is it possible to develop an online calendar, if a u开发者_StackOverflowser clicks on 'Import', all the events should automatically get imported into outlook or iCal?

Importing data into Outlook or iCal can be done using a suitable export format. Direct import would require writing a browser plugin, it's possible but probably not feasible.

More or less. Certainly you can provide data in the standard iCal format (and it is used to nice effect on http://conferences.yapceurope.org — having selected which talks you wish to attend at a multitrack conference, it will generate a custom iCal file for you).

That works with Google Calendar and with Apple iCal. I have no idea what Microsoft Outlook supports.