Google Calendar - Spend less time managing your day & more time enjoying it
Cal.et - Add to Calendar Link Generator
Teamup Calendar - Cloud-based calendaring using capability URL, application developed in Zurich, Switzerland.
Microsoft Outlook Calendar - Calendar is a time-management web application by Microsoft.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
AddEvent - AddEvent is an Add to Calendar button for one-time and multiple events.