Raft Calendar - A fun and beautiful calendar for couples and close friends
Teamup Calendar - Cloud-based calendaring using capability URL, application developed in Zurich, Switzerland.
Ddays - Plan events with friends without the back and forth messages
Campaign Calendar - Campaign Calendar by Bracket Labs builds a marketing calendar from your Salesforce Campaigns.
Evedo - Events done better
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.