What are some alternatives?
When comparing OfficeCalendar and VCalendar, you can also consider the following products
Google Calendar - Spend less time managing your day & more time enjoying it
Teamup Calendar - Cloud-based calendaring using capability URL, application developed in Zurich, Switzerland.
Campaign Calendar - Campaign Calendar by Bracket Labs builds a marketing calendar from your Salesforce Campaigns.
UpTo - Life goes beyond meetings and appointments
Cronofy - Unified Calendar API for developers
CalendarX - Get a calendar your audience can follow