The list of open source calendar software we can supply or host, install, configure, and support (at the time of writing) is as follows :-

Title	Version	Description	Rating
PHP-Calendar	1.0	A web-based calendar and event scheduled written in PHP.
phpScheduleIt	1.2.11	A web-based resource scheduling system that allows administered management of reservations on any number of resources, such as conference rooms.
Plans	7.10	Plans lets you put calendars on the web.
WebCalendar	1.2.0	A PHP application used to maintain a calendar for one or more persons and for a variety of purposes.

If there is a title that is missing off this list we might be able to install it for you.