Stuff to look into later:
http://www.w3.org/2001/sw/Europe/200210/calendar/vocab_usecases.html#xcal
http://www.aspnetemail.com/help/welcome/samples/calendaring/default.html
http://www.bitrot.de/plan.html
http://www.russellbeattie.com/notebook/1004338.html
http://www.phpbuilder.com/columns/chow20021007.php3?page=5
http://farm.tucows.com/blog/Other/_archives/2004/11/2/173619.html
http://www.prism.gatech.edu/%7Egte267v/iCalendarFormat.html
http://www.kanzaki.com/docs/ical/
LDAP:
http://www.openldap.org/
http://www.tldp.org/HOWTO/LDAP-HOWTO/