Teamup Calendar - Cloud-based calendaring using capability URL, application developed in Zurich, Switzerland.
Future - Calendar events around the clock
Campaign Calendar - Campaign Calendar by Bracket Labs builds a marketing calendar from your Salesforce Campaigns.
Event Calendar App - A simple, easy to manage, way of displaying events
ApPHP Calendar - ApPHP Calendar is a PHP calendar script that may be easily integrated and used with various PHP projects, such as schedulers, event, etc.
Loxi - Easily add an events calendar to any website.