Day/week/month/year views

Advanced “recurring event” settings

Event subscriptions: Receive reminders and notifications by event or event type

Warnings about conflicting events

Microformats support

Integrate a calendar month view, or an upcoming events view, onto your design

Supports categories: Have multiple event types

Multiple time zones: Have different events in different time zones with configurable conversion settings.

Priority flagging: Choose between 5 priorities

Programmers can even use the calendar to schedule custom tasks (Commandr) to be run

RSS and Atom support: Export support, but also support for overlaying news feeds onto the calendar.

Supports geotargeting

Feedback: Allow members to comment and rate events. Segregate feedback on recurring events by date.