https://civicrm.org/extensions/contact-calendar
http://emphanos.com/new/civicrm-activities-in-outlook-and-google-calendar/
http://www.ehow.com/how_12201992_sync-outlook-drupal.html
https://github.com/iCalcreator/iCalcreator
https://www.google.com/search?q=mysql+ical+feed&ie=utf-8&oe=utf-8
http://stevethomas.com.au/php/how-to-build-an-ical-calendar-with-php-and-mysql.html
php coding http://www.codeigniter.com/user_guide/
http://stackoverflow.com/questions/6661288/how-to-create-a-ical-ics-feed-in-php
http://stackoverflow.com/questions/8908066/importing-ical-calendar-into-mysql-database
http://www.dhtmlx.com/blog/ical-exportimport-tool-for-dhtmlxscheduler/
https://www.google.com/search?q=mysql+cal+dav+server&ie=utf-8&oe=utf-8
http://radicale.org/project_description/
https://www.linux.com/learn/tutorials/402382:the-five-best-open-source-calendar-servers-for-linux