Teamup Calendar - Cloud-based calendaring using capability URL, application developed in Zurich, Switzerland.
Teamweek - A project management software to help you get the best overview. Plan fast, change plans faster!
UpTo - Life goes beyond meetings and appointments
Kin Calendar - The simple and connected calendar
Google Calendar - Spend less time managing your day & more time enjoying it
Campaign Calendar - Campaign Calendar by Bracket Labs builds a marketing calendar from your Salesforce Campaigns.