In lieu of full fledged event management plugin (specifically event registration/signup), the following added features would help to make this plugin more functional.
1. Add functionality to the Description box - add some buttons to the description box like: bold, italic, LINK (especially). this way non-html folks can add a link to their event registration form or more info or whatever with a click of a button.
Alternately you could had an input field for a hyperlink. That would be very useful for linking to more information or a separate registration form.
2. Add the ability to include an end time (basic event stuff).
3. Ability to upload a photo would also be nice.