Thanks goes to:

Mark James: http://www.famfamfam.com/lab/icons/silk/
	- For the refresh button and many other icons.
	
Chad Little, Patrick Crowley and the PHP iCalendar team: http://phpicalendar.net/
	- For inspiration for the frontend look and feel.
	- For a iCal-powered frontend view in early versions.
	
The Horde Project: http://www.horde.org
	- For the iCalendar import classes.
	
Rupert Germann and other tt_news developers: http://www.rgdata.de/
	- For the category treeview and many other code examples.