Love the Events calendar! And... Here are some enhancements that would make it even better (#1, #2, and #3 are highest priority in my perspective):

1) Ability to duplicate an event (duplicate all data and allow editing from there)

2) Ability for members to un-register from an event (currently, if you register, you can't unregister yourself)

3) For repeating events, ability to register for ALL events in the series or just ONE event in the series (and, set this as an admin toggle, too -- allow registration for all events in the series or just single events)

4) Ability to trigger workflows from an event registration (would need multiple types of filters in the trigger; e.g., a specific event; any event in a particular community group; a keyword in the event title, etc.)

5) Add event registration to Client Portal Admin Notifications section (e.g., when someone registers, an admin notice gets sent out (which could also be handled if workflows had an event trigger))