Remind is a full-featured calendar/reminder program featuring sophisticated date calculation, moon phases, sunrise/sunset, Hebrew calendar, alarms, PostScript output, an X front-end, multilingual messages, and proper handling of holidays. It also includes scripts for making a nice WWW calendar server.
Wcal is a Web-based calendar and planner especially suitable for multi-user setups in an intranet. It features the ability for several users to have their own or shared calendars, read-only views, Weekly and monthly repeating events. It uses the Web server's access control methods, and allows a separate access control definition for each user.