WebCalendar is a PHP application used to maintain a calendar for a single user or an intranet group of users. It can also be configured as an event calendar.
I have used this open source calendar several times. It is robust for a shared calendar - works across multi time zones. If you have several users who need to have varied access to a shared calendar this will do it. You can also use this for a public calendar. BUT there is NO support. No experts who will answer questions. The documentation is only OK. But it has gaps which will suck your time. It installs easily and does the basics. This code needs new owner/champions. I think there is a real need for this exact sort of open source calendar. Please someone do this..... I would pay for support if it was out there.
Seems to have most things i need BUT... Themes look awful. Need a compact One-Day-Per-Line Yearly theme that displays only dates that have events. ie: Date - Event 22-Dec 13 - This Event is happening , click to see full details for the event. 01-Feb-14 - Another Event happening , click to see full details for the event. and so on for a selectable number start and stop days/months. Otherwise, quite a powerful software. Maybe I can pay someone to make a new theme for this?