Teamup Calendar - Cloud-based calendaring using capability URL, application developed in Zurich, Switzerland.
Google Calendar - Spend less time managing your day & more time enjoying it
Kin Calendar - The simple and connected calendar
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
VCalendar - VCalendar is an open source Web calendar application for posting and maintaining events and schedules online.
iCal - In Calendar on your Mac, subscribe to calendars published or shared by others.